[PATCH v3 7/13] drm/vino: add control-session bring-up

[Mike Lothian]

Bringing a dock up runs once per bind, in order: a plaintext initialisation
preamble, the link AKE, then the sealed setup burst that authenticates each
downstream connector, transitions the video engine and reads back what the
dock will answer. The burst's ordering and its spacing both come from the
vendor, and a dock driven faster than it stays dark.

Add the three stages as three modules, and the interrupt-endpoint reader
that decodes what the dock pushes rather than counting it and discarding
the bytes.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Mike Lothian <mike@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/vino/session.rs         |  625 ++++++++++
 drivers/gpu/drm/vino/session/replies.rs |  337 ++++++
 drivers/gpu/drm/vino/session/setup.rs   | 1390 +++++++++++++++++++++++
 3 files changed, 2352 insertions(+)
 create mode 100644 drivers/gpu/drm/vino/session.rs
 create mode 100644 drivers/gpu/drm/vino/session/replies.rs
 create mode 100644 drivers/gpu/drm/vino/session/setup.rs

diff --git a/drivers/gpu/drm/vino/session.rs b/drivers/gpu/drm/vino/session.rs
new file mode 100644
index 000000000000..f14a0f47311e
--- /dev/null
+++ b/drivers/gpu/drm/vino/session.rs
@@ -0,0 +1,625 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Bringing a dock's encrypted control session up.
+//!
+//! In order: the plaintext initialisation preamble, the HDCP 2.2 link AKE, then the sealed control
+//! setup that authenticates each downstream connector and reads its EDID. Everything here runs
+//! once per bind, on the bring-up worker; the steady-state keepalive and the KMS transactions live
+//! in [`super::drm_sink`].
+
+use super::*;
+
+mod replies;
+mod setup;
+
+impl VinoDriver {
+    /// Initialize the plaintext control transport.
+    pub(super) fn bring_up(link: &UsbLink<'_>, profile: &DockProfile) -> Result {
+        // Control-request preamble: dock identity, interface selection, then the
+        // vendor-OUT 0x24 / vendor-IN 0x22 pair that starts the HDCP path.
+        const VENDOR_OUT: u8 = 0x40; // host->link, vendor, device
+        const VENDOR_IN_IFACE: u8 = 0xc1; // device-to-host, vendor, interface recipient
+
+        // Individual vendor requests may stall. Only bulk initialization and
+        // its acknowledgment are required.
+        let mut identity_bytes = [0u8; 16];
+        match link.control_recv(
+            0xfe,
+            VENDOR_IN_IFACE,
+            0,
+            1,
+            &mut identity_bytes,
+            timeout(),
+            GFP_KERNEL,
+        ) {
+            // The raw blob is printed only when it cannot be read as an identity, which is the
+            // case where someone has to decode it by hand. Info, not debug: on unfamiliar
+            // hardware this is what places the device, and needing a debug build to see it costs
+            // a whole test round trip.
+            Ok(()) => match firmware::Identity::parse(&identity_bytes) {
+                // The DFU interface names the dock at info level, so one that parses is already
+                // reported once.
+                Some(id) => vino_debug!("{id} running firmware {}\n", id.version),
+                None => pr_info!("unrecognised device identity = {identity_bytes:02x?}\n"),
+            },
+            Err(e) => pr_info!("device identity unavailable ({e:?})\n"),
+        }
+        // A composite driver may only change its own interface.
+        match link.set_alternate_setting(0) {
+            Ok(()) => {}
+            Err(e) => vino_debug!("vino: alternate setting unchanged ({e:?})\n"),
+        }
+        // The first vendor transition is platform-specific even though both platforms use the
+        // same request number. Ridge uses wValue=3; both occurrences in the authenticated
+        // Navarro/DLM USB transcript use wValue=0. Sending Ridge's value here still permits AKE
+        // and an exact EP02 transcript, but leaves Navarro's video-side state machine different
+        // before its later value-0 commit.
+        let vendor_state = profile.protocol.initial_vendor_state;
+        match link.control_send(
+            0x24,
+            VENDOR_OUT,
+            vendor_state,
+            0,
+            &[],
+            timeout(),
+            GFP_KERNEL,
+        ) {
+            Ok(()) => {}
+            Err(e) => vino_debug!("vino: vendor preamble request stalled ({e:?})\n"),
+        }
+        // Request interface 0 state using the vendor interface recipient.
+        let mut state = [0u8; 28];
+        match link.control_recv(
+            0x22,
+            VENDOR_IN_IFACE,
+            1,
+            0,
+            &mut state,
+            timeout(),
+            GFP_KERNEL,
+        ) {
+            Ok(()) => vino_debug!("vino: interface state = {state:02x?}\n"),
+            Err(e) => vino_debug!("vino: interface state unavailable ({e:?})\n"),
+        }
+
+        // The dock requires this exact plaintext initialization order. It acknowledges the
+        // sequence only after `init_4` and the following probe. The interleaved descriptor reads
+        // are best-effort because a short reply still completes the required control transfer.
+        const STD_IN: u8 = 0x80; // link->host, standard, device
+        let mut config_descriptor = KVec::from_elem(0u8, 618, GFP_KERNEL)?;
+        let _ = link.control_recv(
+            0x06,
+            STD_IN,
+            0x0200,
+            0,
+            &mut config_descriptor[..40],
+            timeout(),
+            GFP_KERNEL,
+        ); // CONFIG, 40
+        let _ = link.control_recv(
+            0x06,
+            STD_IN,
+            0x0200,
+            0,
+            &mut config_descriptor,
+            timeout(),
+            GFP_KERNEL,
+        );
+
+        // Report EP02's maximum packet size because exact-multiple messages require an explicit
+        // terminating short packet.
+        {
+            let total = ((config_descriptor[2] as usize) | ((config_descriptor[3] as usize) << 8))
+                .min(config_descriptor.len());
+            let mut i = 0usize;
+            while i + 2 <= total {
+                let blen = config_descriptor[i] as usize;
+                if blen == 0 {
+                    break;
+                }
+                if config_descriptor[i + 1] == 0x05
+                    && i + 7 <= total
+                    && config_descriptor[i + 2] == EP_CTRL_OUT
+                {
+                    let wmax = (config_descriptor[i + 4] as u16)
+                        | ((config_descriptor[i + 5] as u16) << 8);
+                    vino_debug!("vino: EP02 max packet size {wmax}\n");
+                }
+                i += blen;
+            }
+        }
+
+        let send_required = |label: &str, msg: &[u8]| -> Result {
+            match link.ctrl_send(msg, timeout(), GFP_KERNEL) {
+                Ok(_) => Ok(vino_debug!("vino: sent {label} ({} bytes)\n", msg.len())),
+                Err(e) => {
+                    pr_err!("vino: {label} failed ({e:?})\n");
+                    Err(e)
+                }
+            }
+        };
+        send_required("init_0", &proto::init_0()?)?;
+        send_required("init_25", &proto::init_25()?)?;
+        // Two required string reads between `init_25` and `init_4`.
+        let _ = link.control_recv(
+            0x06,
+            STD_IN,
+            0x0300,
+            0x0000,
+            &mut config_descriptor[..255],
+            timeout(),
+            GFP_KERNEL,
+        ); // STRING #0
+        let _ = link.control_recv(
+            0x06,
+            STD_IN,
+            0x0303,
+            0x0409,
+            &mut config_descriptor[..255],
+            timeout(),
+            GFP_KERNEL,
+        ); // STRING #3 en-US
+        send_required("init_4+probe", &proto::init_4_probe()?)?;
+
+        // Read the single ACK that follows init_4+probe.
+        let mut ack = KVec::from_elem(0u8, 1024, GFP_KERNEL)?;
+        match link.ctrl_recv(&mut ack, timeout(), GFP_KERNEL) {
+            Ok(n) => vino_debug!(
+                "vino: session-init ACK = {n} bytes: {:02x?}\n",
+                &ack[..n.min(40)]
+            ),
+            Err(e) => {
+                pr_err!("vino: session acknowledgment failed ({e:?})\n");
+                return Err(e);
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Number of display connectors the post-msg0 CP setup burst re-states the AKE for. Tied to the
+    /// single connector-count knob `drm_sink::MAX_CONNECTORS` so bumping the connector count is a
+    /// one-line change (was a duplicated literal `2` that had to be kept in sync by hand).
+    pub(super) const CP_SETUP_CONNECTORS: usize = drm_sink::MAX_CONNECTORS;
+
+    /// Reads the next HDCP response (type=4 sub=0x25, sec 5.2) from EP `0x84`,
+    /// skipping any non-HDCP frames (e.g. plain ACKs) in between, and returns the
+    /// parsed `(msg_id, payload)`. Bounded retry so a chatty dock can't wedge us.
+    fn recv_hdcp(link: &UsbLink<'_>) -> Result<(u8, KVec<u8>)> {
+        const SUB_HDCP_RESP: u16 = 0x25;
+        // The dock interleaves capability blocks up to ~5.8 KiB into the AKE reply
+        // stream; size the buffer like the rest of the EP84 reads ([`EP84_BUF`]) so a
+        // large frame is read whole rather than truncated/`-EOVERFLOW`'d.
+        let mut buf = KVec::from_elem(0u8, EP84_BUF, GFP_KERNEL)?;
+        for _ in 0..24 {
+            // The dock interleaves status and capability pushes with the HDCP replies.
+            let n = link.ctrl_recv(&mut buf, timeout(), GFP_KERNEL)?;
+            if n < 16 {
+                continue;
+            }
+            // Include interleaved capability and status frames in dynamic-debug output.
+            {
+                let wsub = u16::from_le_bytes([buf[8], buf[9]]);
+                let iid = if n >= 18 {
+                    u16::from_le_bytes([buf[16], buf[17]])
+                } else {
+                    0
+                };
+                let isub = if n >= 20 {
+                    u16::from_le_bytes([buf[18], buf[19]])
+                } else {
+                    0
+                };
+                vino_debug!(
+                    "vino: AKE-EP84 {n}B wsub={wsub:#x} inner_id={iid:#x} inner_sub={isub:#x}\n"
+                );
+            }
+            if u16::from_le_bytes([buf[8], buf[9]]) != SUB_HDCP_RESP {
+                continue; // non-HDCP frame -- skip
+            }
+            if let Some((id, payload)) = ake::parse_in(&buf[16..n]) {
+                // Inner msg_id 0 is a status/ACK frame (the dock emits one as a
+                // sub=0x25 frame after each OUT message, e.g. the `14 00 76 00...`
+                // frame after AKE_Init) -- skip it and keep reading for the real
+                // HDCP response, mirroring the oracle's recv_hdcp_msg.
+                if id == 0 {
+                    continue;
+                }
+                let mut pl = KVec::with_capacity(payload.len(), GFP_KERNEL)?;
+                pl.extend_from_slice(payload, GFP_KERNEL)?;
+                return Ok((id, pl));
+            }
+        }
+        Err(EINVAL)
+    }
+
+    /// Drain one repeater-authentication acknowledgment before the next request.
+    ///
+    /// The dock enforces request/reply lockstep during this phase. The drain is bounded and
+    /// best-effort so an idle dock cannot stall teardown.
+    fn pace_cap_ack(link: &UsbLink<'_>, want_ctr: u16, saw_cap_complete: &mut bool) {
+        // EP84 frames here can carry an interleaved capability block up to ~5.8 KiB;
+        // size to [`EP84_BUF`] so a large frame isn't truncated mid-pacing.
+        let Ok(mut buf) = KVec::from_elem(0u8, EP84_BUF, GFP_KERNEL) else {
+            return;
+        };
+        for _ in 0..8 {
+            match link.ctrl_recv(&mut buf, Delta::from_millis(30), GFP_KERNEL) {
+                Ok(len) if len >= 22 => {
+                    let wsub = u16::from_le_bytes([buf[8], buf[9]]);
+                    let iid = u16::from_le_bytes([buf[16], buf[17]]);
+                    let isub = u16::from_le_bytes([buf[18], buf[19]]);
+                    let ictr = u16::from_le_bytes([buf[20], buf[21]]);
+                    if iid == 0x0b && isub == 0x84 {
+                        *saw_cap_complete = true;
+                    }
+                    // The per-frame cap-ack: wsub=0x25, inner id=0x14 sub=0x10 ctr=want.
+                    // An interleaved cap push (sub=0x84) or earlier ack -- keep reading.
+                    if wsub == 0x25 && iid == 0x14 && ictr == want_ctr {
+                        return;
+                    }
+                }
+                // A short frame (header-only ack/keepalive): not our cap-ack, but the
+                // dock is still talking -- keep pacing rather than bailing out.
+                Ok(_) => continue,
+                // Nothing queued within the short window -- the dock is idle, don't block.
+                Err(_) => return,
+            }
+        }
+    }
+
+    /// Drain the terminal capability burst before arming the encrypted control plane.
+    ///
+    /// The terminal markers are capability-complete (`id=0x0b sub=0x84`) and
+    /// `RepeaterAuth_Stream_Ready`. If the latter is absent, a bounded quiet interval after the
+    /// capability marker is accepted for firmware compatibility.
+    fn wait_cap_complete(link: &UsbLink<'_>, kd: &[u8; 32], mut saw_0b: bool) {
+        let Ok(mut buf) = KVec::from_elem(0u8, EP84_BUF, GFP_KERNEL) else {
+            return;
+        };
+        // M' verification is diagnostic until every vendor stream-management field is decoded.
+        let sha_kd = crypto::sha256(kd);
+        let mut saw_ready = false;
+        let mut quiet = 0usize;
+        const QUIET_GAP: usize = 3; // ~3 consecutive empty short reads => dock done pushing
+        const MAX_ROUNDS: usize = 48;
+        for _ in 0..MAX_ROUNDS {
+            match link.ctrl_recv(&mut buf, Delta::from_millis(5), GFP_KERNEL) {
+                Ok(len) if len >= 20 => {
+                    quiet = 0;
+                    let iid = u16::from_le_bytes([buf[16], buf[17]]);
+                    let isub = u16::from_le_bytes([buf[18], buf[19]]);
+                    let mid = if len >= 26 { buf[25] } else { 0 }; // HDCP msg_id (body[9])
+                    if isub == 0x84 && iid == 0x0b {
+                        saw_0b = true;
+                    }
+                    if mid == ake::id::REPEATERAUTH_STREAM_READY && len >= 58 {
+                        saw_ready = true;
+                        let mprime = &buf[26..58];
+                        vino_debug!("vino: AKE: Stream_Ready (0x11) M'={mprime:02x?}\n");
+                        // The content-stream-management input contains two
+                        // seven-byte stream entries and a three-byte sequence.
+                        let m_data: [u8; 17] = [
+                            0, 0, 0, 0x04, 0, 0, 0, // stream 0: StreamID_Type[0]
+                            0, 0, 0, 0x05, 0, 0, 0, // stream 1: StreamID_Type[1]
+                            0, 0, 0, // seq_num_M = 0 (first Stream_Manage, big-endian)
+                        ];
+                        let m = crypto::hmac_sha256(&sha_kd, &m_data);
+                        let eq = if &m[..] == mprime { "==" } else { "!=" };
+                        vino_debug!("vino: AKE:   M {} M' (CSM stream-entry layout)\n", eq);
+                    } else if mid == ake::id::RECEIVER_AUTH_STATUS && len >= 27 {
+                        vino_debug!("vino: AKE: RECEIVER_AUTH_STATUS=0x{:02x}\n", buf[26]);
+                    }
+                    // Both terminal markers complete the burst; do not add a quiet delay here.
+                    if saw_0b && saw_ready {
+                        vino_debug!("vino: repeater authentication complete\n");
+                        return;
+                    }
+                }
+                // Empty/short read = a quiet window. Fallback when Stream_Ready (0x11) never
+                // arrives:
+                // once id=0x0b has arrived AND the dock has been quiet for QUIET_GAP rounds, the
+                // terminal burst is drained -- arm now.
+                _ => {
+                    if saw_0b {
+                        quiet += 1;
+                        if quiet >= QUIET_GAP {
+                            vino_debug!("vino: repeater reply drained (ready={saw_ready})\n");
+                            return;
+                        }
+                    }
+                }
+            }
+        }
+        vino_debug!("vino: repeater drain ended (complete={saw_0b}, ready={saw_ready})\n");
+    }
+
+    /// Run HDCP 2.2 AKE, locality check, session-key exchange and repeater authentication.
+    ///
+    /// `H'`, `L'` and `V'` are verified locally. Outbound messages use `type=4 sub=0x04` and the
+    /// inner sequence is:
+    ///
+    /// * ctr=1 session-init ACK (id=0x14/0x76), ctr=2 AKE_Init, ctr=3 AKE_Transmitter_Info
+    /// * ctr=4 AKE_No_Stored_km, ctr=5 LC_Init, ctr=6 SKE_Send_Eks
+    /// * ctr=7 RepeaterAuth_Send_Ack, ctr=8 RepeaterAuth_Stream_Manage  (then msg0 at ctr=9)
+    pub(super) fn run_ake(link: &UsbLink<'_>) -> Result<Session> {
+        use ake::id;
+
+        let mut saw_cap_complete = false;
+
+        // A warm rebind can leave replies from the previous session queued on EP84.
+        let flush_probe = Delta::from_millis(3);
+        if let Ok(mut flush) = KVec::from_elem(0u8, EP84_BUF, GFP_KERNEL) {
+            let mut flushed = 0usize;
+            for _ in 0..32 {
+                match link.ctrl_recv(&mut flush, flush_probe, GFP_KERNEL) {
+                    Ok(n) if n > 0 => flushed += 1,
+                    _ => break,
+                }
+            }
+            if flushed > 0 {
+                vino_debug!("vino: flushed {flushed} stale EP84 frame(s) before AKE\n");
+            }
+        }
+
+        // The setup phase continues this counter through `Session::next_ctr`.
+        let mut hseq: u32 = 1;
+
+        // (1) session-init ACK (ctr=1, id=0x14/0x76).
+        link.ctrl_send(&ake::session_init_ack(hseq, 0)?, timeout(), GFP_KERNEL)?;
+        // The dock requires the counter-1 echo to be drained before AKE_Init.
+        Self::pace_cap_ack(link, hseq as u16, &mut saw_cap_complete);
+        hseq += 1;
+
+        // (2) AKE_Init -- use a fresh rtx and the transmitter capability profile.
+        let mut rtx = [0u8; drm_hdcp::RTX_LEN];
+        rng::fill(&mut rtx);
+        link.ctrl_send(
+            &ake::ake_init(hseq, 0, &rtx, &[0; 3])?,
+            timeout(),
+            GFP_KERNEL,
+        )?;
+        hseq += 1;
+
+        // (2) AKE_Send_Cert: payload = REPEATER(1) || cert_rx(522). Extract the
+        // RSA-1024 public key (modulus[5..133], exponent[133..136]).
+        let (cid, cert_msg) = Self::recv_hdcp(link)?;
+        const CERT_KEY_END: usize = 5 + drm_hdcp::RSA_MODULUS_LEN + drm_hdcp::RSA_EXPONENT_LEN;
+        if cid != id::AKE_SEND_CERT || cert_msg.len() < 1 + CERT_KEY_END {
+            pr_err!(
+                "vino: AKE: bad AKE_Send_Cert (id={cid:#x}, {} B)\n",
+                cert_msg.len()
+            );
+            return Err(EINVAL);
+        }
+        let repeater = cert_msg[0] != 0;
+        let cert = &cert_msg[1..];
+        let mut modulus = [0u8; drm_hdcp::RSA_MODULUS_LEN];
+        modulus.copy_from_slice(&cert[5..5 + drm_hdcp::RSA_MODULUS_LEN]);
+        let mut exponent = [0u8; drm_hdcp::RSA_EXPONENT_LEN];
+        exponent.copy_from_slice(&cert[5 + drm_hdcp::RSA_MODULUS_LEN..CERT_KEY_END]);
+
+        // (3) AKE_Transmitter_Info (ctr=3), then read AKE_Receiver_Info (RxCaps unused).
+        link.ctrl_send(&ake::ake_transmitter_info(hseq, 0)?, timeout(), GFP_KERNEL)?;
+        hseq += 1;
+        let _ = Self::recv_hdcp(link)?;
+
+        // (5) AKE_No_Stored_km -- fresh km, RSA-OAEP-SHA256 to Ekpub(km).
+        let mut km = kernel::crypto::Secret::<{ drm_hdcp::ENCRYPTED_SESSION_KEY_LEN }>::zeroed();
+        rng::fill(&mut km[..]);
+        let mut rsa = kernel::crypto::akcipher::RsaPublicKey::new(&modulus, &exponent, GFP_KERNEL)?;
+        let ekpub = hdcp::oaep_encrypt_km(&mut rsa, &km)?;
+        // (4) AKE_No_Stored_km (ctr=4). The dock authenticates its downstream link before it
+        // answers, so the following receive naturally covers that interval.
+        link.ctrl_send(
+            &ake::ake_no_stored_km(hseq, 0, &ekpub)?,
+            timeout(),
+            GFP_KERNEL,
+        )?;
+        hseq += 1;
+
+        // (6) AKE_Send_Rrx.
+        let (rid, rrx_pl) = Self::recv_hdcp(link)?;
+        if rid != id::AKE_SEND_RRX || rrx_pl.len() < drm_hdcp::RRX_LEN {
+            pr_err!("vino: AKE: bad AKE_Send_Rrx (id={rid:#x})\n");
+            return Err(EINVAL);
+        }
+        let mut rrx = [0u8; drm_hdcp::RRX_LEN];
+        rrx.copy_from_slice(&rrx_pl[..drm_hdcp::RRX_LEN]);
+
+        // (7)/(8) AKE_Send_H_prime -- verify H' = HMAC(kd, rtx^REPEATER).
+        let (hid, hp) = Self::recv_hdcp(link)?;
+        if hid != id::AKE_SEND_H_PRIME || hp.len() < drm_hdcp::H_PRIME_LEN {
+            pr_err!("vino: AKE: bad H' (id={hid:#x})\n");
+            return Err(EINVAL);
+        }
+        let kd = hdcp::derive_kd(&km, &rtx, &rrx)?;
+        if hdcp::compute_h(&kd, &rtx, repeater)[..] != hp[..drm_hdcp::H_PRIME_LEN] {
+            pr_err!("vino: AKE: H' mismatch -- authentication failed\n");
+            return Err(EINVAL);
+        }
+        vino_debug!("vino: AKE: H' verified\n");
+
+        // (9) AKE_Send_Pairing_Info (Ekh_km) -- read and discard (no-stored path).
+        let _ = Self::recv_hdcp(link)?;
+
+        // (10) Locality Check -- LC_Init(rn) then verify L'.
+        let mut rn = [0u8; drm_hdcp::RN_LEN];
+        rng::fill(&mut rn);
+        // (5) LC_Init (ctr=5).
+        link.ctrl_send(&ake::lc_init(hseq, 0, &rn)?, timeout(), GFP_KERNEL)?;
+        hseq += 1;
+        let (lid, lp) = Self::recv_hdcp(link)?;
+        if lid != id::LC_SEND_L_PRIME || lp.len() < drm_hdcp::L_PRIME_LEN {
+            pr_err!("vino: AKE: bad L' (id={lid:#x})\n");
+            return Err(EINVAL);
+        }
+        if hdcp::compute_l(&kd, &rrx, &rn)[..] != lp[..drm_hdcp::L_PRIME_LEN] {
+            pr_err!("vino: AKE: L' mismatch -- locality check failed\n");
+            return Err(EINVAL);
+        }
+        vino_debug!("vino: AKE: L' verified\n");
+
+        // (11) Session Key Exchange -- send Edkey(ske_ks) and the fresh RIV. The wrapped value is
+        // the raw SKE key; both peers apply the control-plane whitening constant afterwards.
+        let mut ske_ks =
+            kernel::crypto::Secret::<{ drm_hdcp::ENCRYPTED_SESSION_KEY_LEN }>::zeroed();
+        let mut riv = [0u8; drm_hdcp::RIV_LEN];
+        rng::fill(&mut ske_ks[..]);
+        rng::fill(&mut riv);
+        let edkey = hdcp::compute_eks(&km, &rtx, &rrx, &rn, &ske_ks)?;
+        let ks = cp::cp_session_key(&ske_ks);
+        // SKE carries the full RIV. Control AES-CTR toggles byte 7 bit 2;
+        // Dl3Cmac separately transforms byte 0 bit 7.
+        let riv_ske = riv; // deliver the full random RIV before the control transform
+        riv[7] ^= 0x04; // OUT CP AES-CTR nonce = delivered ^0x04@byte7 (byte0 UNCHANGED)
+                        // (6) SKE_Send_Eks (ctr=6).
+        link.ctrl_send(
+            &ake::ske_send_eks(hseq, 0, &edkey, &riv_ske)?,
+            timeout(),
+            GFP_KERNEL,
+        )?;
+        hseq += 1;
+        // (12) RepeaterAuth -- verify V' over the ReceiverID_List, ACK, then SM2. Retained (empty
+        // on the non-repeater path) so `send_cp_setup`'s per-connector restatement can recompute a
+        // fresh per-connector `V = HMAC(kd_h, rxid_list)` over the same list the dock sent.
+        let mut rxid_list: KVec<u8> = KVec::new();
+        if repeater {
+            let (vid, list) = Self::recv_hdcp(link)?;
+            if vid != id::REPEATERAUTH_SEND_RECEIVERID_LIST || list.len() < 16 {
+                pr_err!("vino: AKE: bad ReceiverID_List (id={vid:#x})\n");
+                return Err(EINVAL);
+            }
+            let split = list.len() - 16;
+            // V' is the first 128 bits; RepeaterAuth_Send_Ack carries the second 128 bits.
+            let v_full = hdcp::compute_v_full(&kd, &list[..split]);
+            let mut v_ack = [0u8; 16];
+            v_ack.copy_from_slice(&v_full[16..]);
+            if v_full[..16] != list[split..] {
+                pr_err!("vino: AKE: V' mismatch -- repeater verification failed\n");
+                return Err(EINVAL);
+            }
+            vino_debug!("vino: AKE: V' verified\n");
+            rxid_list.extend_from_slice(&list[..split], GFP_KERNEL)?;
+            // (7) RepeaterAuth_Send_Ack (ctr=7).
+            link.ctrl_send(
+                &ake::repeater_auth_send_ack(hseq, 0, &v_ack)?,
+                timeout(),
+                GFP_KERNEL,
+            )?;
+            // Preserve repeater-authentication request/reply lockstep.
+            Self::pace_cap_ack(link, hseq as u16, &mut saw_cap_complete);
+            hseq += 1;
+            // (8) RepeaterAuth_Stream_Manage (ctr=8).
+            link.ctrl_send(
+                &ake::repeater_auth_stream_manage(hseq, 0)?,
+                timeout(),
+                GFP_KERNEL,
+            )?;
+            Self::pace_cap_ack(link, hseq as u16, &mut saw_cap_complete);
+            hseq += 1;
+            // Drain capability-complete and Stream_Ready before arming the control plane.
+            Self::wait_cap_complete(link, &kd, saw_cap_complete);
+        }
+
+        // `hseq` points past the last capability/AKE frame; `send_cp_setup` continues the inner
+        // counter from here for msg0.
+        if trace_crypto_enabled() {
+            pr_info!(
+                "vino-crypto: control key={:02x?} riv_out={riv:02x?} next_ctr={}\n",
+                &ks[..],
+                hseq
+            );
+        }
+        Ok(Session {
+            ks,
+            riv,
+            next_ctr: hseq as u16,
+            rsa,
+            rxid_list,
+        })
+    }
+
+    /// Submit one encrypted control-plane frame without changing protocol counters on failure. Name
+    /// a connector's content stream, on a dock where that is a control-plane record.
+    ///
+    /// A dock whose video shares the control pipe has no video endpoint to open a stream on later,
+    /// so every connector it may ever drive has to be named during setup -- including one whose
+    /// downstream authentication did not run, because a monitor plugged in afterwards comes up on
+    /// exactly that connector and would then be driven on a stream the dock was never told about.
+    /// The vendor names both connectors unconditionally. Docks with a video pipe of their own carry
+    /// this ahead of the first frame instead, so they get nothing here.
+    fn announce_stream(
+        link: &UsbLink<'_>,
+        out_q: &mut Option<usb::BulkOutQueue>,
+        profile: &DockProfile,
+        connector: usize,
+    ) -> Result {
+        if !profile.topology.video_on_ctrl_pipe {
+            return Ok(());
+        }
+        let stream_id = profile.geometry().stream_id(connector as u8);
+        Self::submit_cp_frame(
+            link,
+            out_q,
+            &cp::stream_announce(stream_id, cp::STREAM_ANNOUNCE_MARKER),
+        )
+    }
+
+    fn submit_cp_frame(
+        link: &UsbLink<'_>,
+        out_q: &mut Option<usb::BulkOutQueue>,
+        frame: &[u8],
+    ) -> Result {
+        match out_q {
+            // The queued path, which is the one both docks actually use. An error here is what
+            // surfaces as `control session failed after N attempts (ETIMEDOUT)`; the 40-retry NAK
+            // loop further down is the *unqueued* fallback and does not run, which is why
+            // instrumenting it said nothing.
+            Some(queue) => queue.send(link.io(), frame, timeout()).inspect_err(|e| {
+                pr_err!(
+                    "vino: EP02 queued submit of {} B failed ({e:?})\n",
+                    frame.len()
+                );
+            }),
+            None => link.ctrl_send(frame, timeout(), GFP_KERNEL).map(|_| ()),
+        }
+    }
+
+    /// Seal and send one live interactive control message.
+    ///
+    /// The OUT is one long-lived URB, then EP84 is drained once after its completion. The returned
+    /// tally distinguishes verified acknowledgments from rejected ciphertext.
+    ///
+    /// Do not implement a short-timeout retry here. A USB bulk timeout does not prove that no
+    /// bytes reached the device: Navarro accepted several complete 64-byte frames just before
+    /// Vino cancelled their 5 ms URBs. Re-submitting the same sealed frame consequently put
+    /// duplicate inner counters on the wire (measured at counters 72, 75 and 95), while DLM sends
+    /// each transaction once. Leaving one URB outstanding lets xHCI retry NRDY packets without
+    /// replaying an already accepted application message.
+    fn send_live_cp(
+        link: &UsbLink<'_>,
+        session: &Session,
+        mut q: Option<&mut usb::BulkInQueue>,
+        resp: &mut [u8],
+        edid_out: &mut Option<KVec<u8>>,
+        id: u16,
+        wire_seq: u32,
+        content: &[u8],
+    ) -> Result<Ep84Drain> {
+        let frame = cp::seal_interactive(&session.ks, &session.riv, id, wire_seq, content)?;
+
+        let mut tally = Ep84Drain::default();
+        link.ctrl_send(&frame, timeout(), GFP_KERNEL)?;
+        // Collect the dock's reply, including a possible get-EDID id=0x194 frame.
+        tally.add(Self::drain_ep84(
+            link,
+            q.as_deref_mut(),
+            resp,
+            session,
+            edid_out,
+            Delta::from_millis(10),
+        ));
+        Ok(tally)
+    }
+}
diff --git a/drivers/gpu/drm/vino/session/replies.rs b/drivers/gpu/drm/vino/session/replies.rs
new file mode 100644
index 000000000000..b86380d7327c
--- /dev/null
+++ b/drivers/gpu/drm/vino/session/replies.rs
@@ -0,0 +1,337 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Reading the dock's interrupt endpoint.
+//!
+//! The dock answers on EP84 and also pushes unsolicited messages there. A reply left undrained
+//! desynchronises the control plane, so the read paths here are what keep the session in lockstep
+//! rather than merely convenient.
+
+use super::*;
+
+impl VinoDriver {
+    /// Log one EP84 wire header and its decoded inner header when available.
+    fn log_ep84(session: &Session, frame: &[u8]) {
+        let len = frame.len();
+        let wtype = if len >= 8 {
+            u32::from_le_bytes([frame[4], frame[5], frame[6], frame[7]])
+        } else {
+            0
+        };
+        let wsub = if len >= 10 {
+            u16::from_le_bytes([frame[8], frame[9]])
+        } else {
+            0
+        };
+        let aux = if len >= 12 {
+            u16::from_le_bytes([frame[10], frame[11]])
+        } else {
+            0
+        };
+        let wseq = if len >= 16 {
+            u32::from_le_bytes([frame[12], frame[13], frame[14], frame[15]])
+        } else {
+            0
+        };
+        {
+            // Bound dynamic-debug output and split large frames below printk's line limit.
+            let cap = len.min(768);
+            if cap <= 64 {
+                let raw = &frame[..cap];
+                vino_debug!("vino: dock EP84 RAW {len}B {raw:02x?}\n");
+            } else {
+                vino_debug!("vino: dock EP84 RAW {len}B (first {cap} B in 128-B chunks):\n");
+                let mut o = 0usize;
+                while o < cap {
+                    let e = (o + 128).min(cap);
+                    let chunk = &frame[o..e];
+                    vino_debug!("vino:   ep84[{o:#06x}] {chunk:02x?}\n");
+                    o = e;
+                }
+            }
+        }
+        match cp::decode_any(&session.ks, &session.riv, frame) {
+            Some((rivtag, rid, rsub, rictr, _)) => {
+                vino_debug!("vino: EP84 {rivtag} id={rid:#x} sub={rsub:#x} ctr={rictr:#x}\n");
+            }
+            None => vino_debug!(
+                "vino: EP84 type={wtype} sub={wsub:#x} aux={aux:#x} seq={wseq:#x} len={len}\n"
+            ),
+        }
+    }
+    /// Read one EP84 frame from the persistent queue or the synchronous fallback.
+    pub(super) fn read_ep84(
+        link: &UsbLink<'_>,
+        q: Option<&mut usb::BulkInQueue>,
+        buf: &mut [u8],
+        to: Delta,
+    ) -> Result<usize> {
+        match q {
+            Some(queue) => match queue.recv(link.io(), buf, to) {
+                Ok(Some(n)) => Ok(n),
+                Ok(None) => Err(ETIMEDOUT),
+                Err(e) => Err(e),
+            },
+            None => link.ctrl_recv(buf, to, GFP_KERNEL),
+        }
+    }
+    pub(super) fn drain_ep84(
+        link: &UsbLink<'_>,
+        mut q: Option<&mut usb::BulkInQueue>,
+        buf: &mut [u8],
+        session: &Session,
+        edid_out: &mut Option<KVec<u8>>,
+        // The first read may cover an HDCP computation interval; subsequent reads only drain a
+        // contiguous reply burst.
+        first_wait: Delta,
+    ) -> Ep84Drain {
+        const MAX_READS: usize = 16;
+        let mut out = Ep84Drain::default();
+        // Read EP84 before doing any unrelated work: the control plane is lockstep.
+        for i in 0..MAX_READS {
+            let wait = if i == 0 {
+                first_wait
+            } else {
+                Delta::from_millis(10)
+            };
+            match Self::read_ep84(link, q.as_deref_mut(), buf, wait) {
+                Ok(len) if len > 0 => {
+                    out.reads += 1;
+                    Self::log_ep84(session, &buf[..len]);
+                    // Decode every downstream-HDCP milestone, not just Rrx.  A generic encrypted
+                    // envelope acknowledgment does not mean the downstream authentication has
+                    // advanced; L', V' and M' are the state-machine gates.
+                    if let Some(push) =
+                        cp::per_connector_hdcp_push(&session.ks, &session.riv, &buf[..len])
+                    {
+                        out.observe_perhead(push);
+                    }
+                    if len >= 10 && u16::from_le_bytes([buf[8], buf[9]]) == 0x45 {
+                        // The 0x45 wire tag is shared by status traffic. Only a valid decrypted
+                        // inner header proves that this session's cipher is engaged.
+                        match cp::verify_in_ack(&session.ks, &session.riv, &buf[..len]) {
+                            Some((id, sub, ctr)) => {
+                                out.acks += 1;
+                                vino_debug!(
+                                    "vino: CP acknowledgment id={id:#x} sub={sub:#x} ctr={ctr}\n"
+                                );
+                                // A display-capability reply identifies a
+                                // present monitor and echoes the request counter.
+                                if cp::is_display_cap_reply(id, sub) {
+                                    out.display_cap_ctr = Some(ctr);
+                                }
+                                // Capture the first `id=0x194 sub=0x21` EDID
+                                // reply for the standard DRM mode helpers.
+                                if edid_out.is_none() {
+                                    if let Ok(Some(e)) = cp::parse_edid_from_reply(
+                                        &session.ks,
+                                        &session.riv,
+                                        &buf[..len],
+                                    ) {
+                                        vino_debug!(
+                                            "vino: EDID read from dock ({} bytes)\n",
+                                            e.len()
+                                        );
+                                        *edid_out = Some(e);
+                                    }
+                                }
+                                // Track the downstream-DDC readiness bit so
+                                // the EDID loop can distinguish pending work.
+                                if let Some(true) =
+                                    cp::edid_poll_ready(&session.ks, &session.riv, &buf[..len])
+                                {
+                                    out.edid_ready = true;
+                                }
+                            }
+                            None => {
+                                match cp::decode_in_lenient(&session.ks, &session.riv, &buf[..len])
+                                {
+                                    // A structurally valid header with an uncatalogued sub-id still
+                                    // proves possession of the session key.
+                                    Some((id, sub, ctr)) => {
+                                        out.acks += 1;
+                                        vino_debug!(
+                                            "vino: CP reply id={id:#x} sub={sub:#x} ctr={ctr}\n"
+                                        );
+                                        if sub == 0x000c {
+                                            if let Some(inner) = cp::inner_plaintext(
+                                                &session.ks,
+                                                &session.riv,
+                                                &buf[..len],
+                                            ) {
+                                                if let Some(line) = cp::dock_trace_line(&inner) {
+                                                    vino_debug!(
+                                                        "vino: dock: {}\n",
+                                                        core::str::from_utf8(&line).unwrap_or("?")
+                                                    );
+                                                }
+                                            }
+                                        }
+                                    }
+                                    // Not a sealed reply. Navarro pushes plaintext-framed
+                                    // messages the dock originates rather than answers, so a
+                                    // frame vino cannot open is only a rejection once that
+                                    // framing has been ruled out too.
+                                    None => match cp::inner_plaintext(
+                                        &session.ks,
+                                        &session.riv,
+                                        &buf[..len],
+                                    ) {
+                                        Some(inner) => {
+                                            out.acks += 1;
+                                            if let Some(line) = cp::dock_trace_line(&inner) {
+                                                vino_debug!(
+                                                    "vino: dock: {}\n",
+                                                    core::str::from_utf8(&line).unwrap_or("?")
+                                                );
+                                            }
+                                        }
+                                        None => {
+                                            out.rejects += 1;
+                                            pr_warn!("vino: invalid encrypted CP reply\n");
+                                        }
+                                    },
+                                }
+                            }
+                        }
+                    }
+                }
+                _ => break,
+            }
+        }
+        out
+    }
+    /// Read through the downstream-HDCP reply stream until one specific protocol milestone.
+    ///
+    /// Navarro acknowledges every encrypted envelope before it emits the corresponding HDCP
+    /// result.  Advancing on the generic ACK alone allowed Vino to send SKE/V-ACK/Stream-Manage
+    /// without ever receiving L', V' or M'.  The dock accepted the envelopes but never enabled
+    /// the video consumer.  This routine makes the HDCP result, rather than the wrapper ACK, the
+    /// sequencing condition.
+    pub(super) fn wait_per_connector_push(
+        link: &UsbLink<'_>,
+        mut q: Option<&mut usb::BulkInQueue>,
+        buf: &mut [u8],
+        session: &Session,
+        want_msg_id: u8,
+        wait: Delta,
+    ) -> Ep84Drain {
+        const MAX_READS: usize = 16;
+        let mut out = Ep84Drain::default();
+        for _ in 0..MAX_READS {
+            match Self::read_ep84(link, q.as_deref_mut(), buf, wait) {
+                Ok(len) if len > 16 => {
+                    out.reads += 1;
+                    Self::log_ep84(session, &buf[..len]);
+                    if let Some(push) =
+                        cp::per_connector_hdcp_push(&session.ks, &session.riv, &buf[..len])
+                    {
+                        out.observe_perhead(push);
+                        if out.saw_perhead(want_msg_id) {
+                            return out;
+                        }
+                        continue;
+                    }
+                    if u16::from_le_bytes([buf[8], buf[9]]) != 0x45 {
+                        continue;
+                    }
+                    match cp::verify_in_ack(&session.ks, &session.riv, &buf[..len]) {
+                        Some((id, sub, ctr)) => {
+                            out.acks += 1;
+                            vino_debug!(
+                                "vino: CP acknowledgment while waiting for HDCP {want_msg_id:#x}: id={id:#x} sub={sub:#x} ctr={ctr}\n"
+                            );
+                        }
+                        None if cp::decode_in_lenient(&session.ks, &session.riv, &buf[..len])
+                            .is_some() =>
+                        {
+                            out.acks += 1;
+                        }
+                        None => {
+                            out.rejects += 1;
+                            pr_warn!("vino: invalid encrypted CP reply\n");
+                        }
+                    }
+                }
+                Ok(_) => continue,
+                Err(_) => break,
+            }
+        }
+        out
+    }
+    /// Drain replies until a verified inner counter echoes the submitted request.
+    ///
+    /// Asynchronous pushes are processed while waiting, and the operation remains bounded.
+    pub(super) fn lockstep_reply(
+        link: &UsbLink<'_>,
+        mut q: Option<&mut usb::BulkInQueue>,
+        buf: &mut [u8],
+        session: &Session,
+        ictr: u16,
+        edid_out: &mut Option<KVec<u8>>,
+    ) -> Ep84Drain {
+        const MAX_READS: usize = 8;
+        let mut out = Ep84Drain::default();
+        for _ in 0..MAX_READS {
+            match Self::read_ep84(link, q.as_deref_mut(), buf, Delta::from_millis(30)) {
+                Ok(len) if len > 16 => {
+                    out.reads += 1;
+                    Self::log_ep84(session, &buf[..len]);
+                    if u16::from_le_bytes([buf[8], buf[9]]) != 0x45 {
+                        continue;
+                    }
+                    if let Some(push) =
+                        cp::per_connector_hdcp_push(&session.ks, &session.riv, &buf[..len])
+                    {
+                        out.observe_perhead(push);
+                    }
+                    match cp::verify_in_ack(&session.ks, &session.riv, &buf[..len]) {
+                        Some((id, sub, ctr)) => {
+                            out.acks += 1;
+                            let echo = if ctr == ictr {
+                                " (echoes our ictr)"
+                            } else {
+                                ""
+                            };
+                            vino_debug!("vino: CP reply id={id:#x} sub={sub:#x} ctr={ctr}{echo}\n");
+                            // Opportunistically extract an EDID from an id=0x194 reply.
+                            if edid_out.is_none() {
+                                if let Ok(Some(e)) = cp::parse_edid_from_reply(
+                                    &session.ks,
+                                    &session.riv,
+                                    &buf[..len],
+                                ) {
+                                    vino_debug!("vino: EDID read from dock ({} bytes)\n", e.len());
+                                    *edid_out = Some(e);
+                                }
+                            }
+                            // Stop early once the dock acknowledges the counter we sent.
+                            if ctr == ictr {
+                                break;
+                            }
+                        }
+                        None => match cp::decode_in_lenient(&session.ks, &session.riv, &buf[..len])
+                        {
+                            // Decrypts to a plausible CP header, just an unlisted `sub` -- a valid
+                            // ack (cipher engaged), not a rejection. See the drain_ep84 branch.
+                            Some((id, sub, ctr)) => {
+                                out.acks += 1;
+                                vino_debug!("vino: CP reply id={id:#x} sub={sub:#x} ctr={ctr}\n");
+                            }
+                            None => {
+                                out.rejects += 1;
+                                pr_warn!("vino: invalid encrypted CP reply\n");
+                            }
+                        },
+                    }
+                }
+                // A short, header-only frame (bare ack/keepalive, len <= 16): not a CP
+                // reply, but the dock is still talking -- keep reading for the 0x45 rather
+                // than dropping the rest of the lockstep window.
+                Ok(_) => continue,
+                // Read error / nothing queued within the window: the dock is idle, stop.
+                Err(_) => break,
+            }
+        }
+        out
+    }
+}
diff --git a/drivers/gpu/drm/vino/session/setup.rs b/drivers/gpu/drm/vino/session/setup.rs
new file mode 100644
index 000000000000..b278ebcf4b4e
--- /dev/null
+++ b/drivers/gpu/drm/vino/session/setup.rs
@@ -0,0 +1,1390 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! The post-authentication setup burst.
+//!
+//! Once the AKE completes the dock still knows nothing about how it is to be driven. This is the
+//! sequence that tells it: the dock-wide records, the per-connector HDCP restatement, the video
+//! engine transition and the connector-selecting records. Its ordering is measured from the
+//! vendor, and a message sent out of turn desynchronises the authenticated counter for the rest of
+//! the session.
+
+use super::*;
+
+impl VinoDriver {
+    /// Configure the encrypted control plane after SKE.
+    ///
+    /// The sequence contains the plaintext arm marker, the first encrypted message, initialization,
+    /// per-connector authentication and stream finalization. The returned counters continue the
+    /// live session, and `video_keys` receives the key and nonce established for each connector.
+    pub(crate) fn send_cp_setup(
+        link: &UsbLink<'_>,
+        profile: &DockProfile,
+        session: &mut Session,
+        // Scratch slot filled by reply drains and moved into the selected connector's EDID cache.
+        edid_out: &mut Option<KVec<u8>>,
+        edid_connectors: &mut [Option<KVec<u8>>; Self::CP_SETUP_CONNECTORS],
+        video_keys: &mut [kernel::crypto::Secret<32>; Self::CP_SETUP_CONNECTORS],
+        connectors_present: &mut [bool; Self::CP_SETUP_CONNECTORS],
+        discovery_deferred: &mut [bool; Self::CP_SETUP_CONNECTORS],
+        // Which connectors had their video stream opened in this burst, as a connector bitmask. A
+        // connector with no sink yet is skipped here and owes its open to whatever drives it later.
+        stream_opened: &mut u32,
+    ) -> Result<(usize, u32, u16)> {
+        let connector_count =
+            usize::from(profile.topology.connectors).min(Self::CP_SETUP_CONNECTORS);
+        // 16 KiB so the dock's ~5787 B capability block is read whole (see [`EP84_BUF`]).
+        let mut resp = KVec::from_elem(0u8, EP84_BUF, GFP_KERNEL)?;
+        let mut drained = 0usize;
+        let mut acks = 0usize;
+        let mut rejects = 0usize;
+        let mut sent = 0usize;
+        // Match each display-capability response to the stream-open counter of its connector.
+        let mut stream_open_ctr: [Option<u16>; Self::CP_SETUP_CONNECTORS] =
+            [None; Self::CP_SETUP_CONNECTORS];
+
+        // Plaintext `type=2 sub=0x24`+`0x45` stream-open arm marker -- the mandatory gate
+        // before the first encrypted frame.
+        const STREAM_OPEN: [u8; 64] = [
+            0x00, 0x00, 0x1c, 0x00, 0x02, 0x00, 0x00, 0x00, // pad, size, type
+            0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // wsub=0x24, aux=0, seq=0
+            0x04, 0x00, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, // payload
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // padding
+            0x00, 0x00, 0x1c, 0x00, 0x02, 0x00, 0x00, 0x00, // pad, size, type
+            0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // wsub=0x45, aux=0, seq=0
+            0x05, 0x00, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, // payload
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // padding
+        ];
+
+        // Post the persistent EP84 reader before arming so asynchronous replies cannot fill the
+        // dock's IN FIFO while the host submits control traffic.
+        let ep84_depth = profile.protocol.ep84_queue_depth;
+        let mut ep84_q = match link.ctrl_in_queue(ep84_depth, EP84_BUF) {
+            Ok(q) => {
+                vino_debug!("vino: EP84 async IN queue opened (depth={ep84_depth})\n");
+                Some(q)
+            }
+            Err(e) => {
+                vino_debug!("vino: EP84 queue unavailable ({e:?}); using synchronous reads\n");
+                None
+            }
+        };
+
+        let mut out_q = match link.ctrl_out_queue(4, 1024) {
+            Ok(q) => {
+                vino_debug!("vino: EP02 async OUT queue opened (depth=4)\n");
+                Some(q)
+            }
+            Err(e) => {
+                vino_debug!("vino: EP02 async OUT queue open failed ({e:?})\n");
+                None
+            }
+        };
+
+        // Submit and flush the arm before sealing the first encrypted message.
+        let arm_res = match out_q.as_mut() {
+            Some(q) => q
+                .send(link.io(), &STREAM_OPEN, timeout())
+                .and_then(|()| q.flush(link.io(), timeout())),
+            None => link
+                .ctrl_send(&STREAM_OPEN, timeout(), GFP_KERNEL)
+                .map(|_| ()),
+        };
+        arm_res?;
+        // The first live message continues the AKE inner counter and starts the encrypted wire
+        // block counter at zero. Every following message advances both counters from its true size.
+        let mut cp_ctr: u16 = session.next_ctr;
+        let mut wseq: u32 = 0;
+
+        let content = cp::session_hello(cp_ctr);
+        let body_len = content.len() + 16; // AES-CTR ciphertext + 16-byte Dl3Cmac
+        let size = ((16 + body_len) - 4) as u16;
+        let aux = cp::aux_for_id(0x14, body_len);
+        let mut hdr = [0u8; 16];
+        hdr[2..4].copy_from_slice(&size.to_le_bytes());
+        hdr[4..8].copy_from_slice(&4u32.to_le_bytes()); // type=4
+        hdr[8..10].copy_from_slice(&0x24u16.to_le_bytes()); // sub=0x24 (interactive CP)
+        hdr[10..12].copy_from_slice(&aux.to_le_bytes());
+        // Running AES-CTR block index, initially zero.
+        hdr[12..16].copy_from_slice(&wseq.to_le_bytes());
+        let frame = cp::seal_livemac(&session.ks, &session.riv, &hdr, &content)?;
+
+        match out_q.as_mut() {
+            Some(q) => {
+                q.send(link.io(), &frame, timeout())?;
+                q.flush(link.io(), timeout())?;
+                if profile.protocol.reply_discipline == profile::ReplyDiscipline::Lockstep {
+                    // DLM advances as soon as the dock authenticates msg0. The old eight-drain
+                    // loop waited for seven empty 10-ms windows after that reply and moved every
+                    // following setup transition roughly 90 ms later on the wire.
+                    let d = Self::lockstep_reply(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        cp_ctr,
+                        edid_out,
+                    );
+                    drained += d.reads;
+                    acks += d.acks;
+                    rejects += d.rejects;
+                } else {
+                    for _ in 0..8 {
+                        let d = Self::drain_ep84(
+                            link,
+                            ep84_q.as_mut(),
+                            &mut resp,
+                            session,
+                            edid_out,
+                            Delta::from_millis(10),
+                        );
+                        drained += d.reads;
+                        acks += d.acks;
+                        rejects += d.rejects;
+                    }
+                }
+            }
+            None => {
+                // A NAK transfers no bytes, so cancel and retry are safe.
+                // Between attempts drain EP84 so the dock can push/drain its IN queue. Bounded.
+                const TRIES: usize = 40;
+                let mut last_err = ETIMEDOUT;
+                let mut accepted = false;
+                // Name what the dock is refusing. This path returns `control session failed ...
+                // (ETIMEDOUT)`, which is otherwise indistinguishable from a reply that never
+                // arrived; the distinction matters because this is the send side, where the dock
+                // has stopped taking EP02 writes at all.
+                let mut nak_reported = false;
+                for _ in 0..TRIES {
+                    match link.ctrl_send(&frame, Delta::from_millis(5), GFP_KERNEL) {
+                        Ok(_) => {
+                            accepted = true;
+                            break;
+                        }
+                        // OUT NAK'd (nothing transferred) -- let the dock push on EP84, then retry.
+                        Err(e) => {
+                            last_err = e;
+                            if !nak_reported {
+                                nak_reported = true;
+                                vino_debug!(
+                                    "vino: EP02 NAKed a {} B control frame (cp_ctr={cp_ctr}, wseq={wseq}); retrying up to {TRIES}x\n",
+                                    frame.len()
+                                );
+                            }
+                            let d = Self::drain_ep84(
+                                link,
+                                ep84_q.as_mut(),
+                                &mut resp,
+                                session,
+                                edid_out,
+                                Delta::from_millis(10),
+                            );
+                            drained += d.reads;
+                            acks += d.acks;
+                            rejects += d.rejects;
+                        }
+                    }
+                }
+                if !accepted {
+                    pr_err!(
+                        "vino: EP02 refused {TRIES} submissions of a {} B frame (cp_ctr={cp_ctr}, wseq={wseq}) -- giving up\n",
+                        frame.len()
+                    );
+                    return Err(last_err);
+                }
+            }
+        }
+        sent += 1;
+        cp_ctr += 1; // past msg0
+        wseq += 2; // msg0 content is 32 B = 2 AES blocks
+
+        // Initialization continues with two dock-wide records and one `0x16/0x2a` record for
+        // every physical connector. The authenticated Navarro transcript carries selectors
+        // 0,1,2,3 here; emitting Ridge's historical pair left all later counters four AES blocks
+        // behind DLM and never initialized Navarro's last two connector slots.
+        macro_rules! send_init {
+            ($id:expr, $sub:expr, $fixed_prefix:expr) => {{
+                let id: u16 = $id;
+                let sub: u16 = $sub;
+                let fixed_prefix: &[u8] = $fixed_prefix;
+                let mut c = [0u8; 32];
+                c[0..2].copy_from_slice(&id.to_le_bytes());
+                c[2..4].copy_from_slice(&sub.to_le_bytes());
+                c[4..6].copy_from_slice(&cp_ctr.to_le_bytes());
+                rng::fill(&mut c[22..32]);
+                c[22..22 + fixed_prefix.len()].copy_from_slice(fixed_prefix);
+                let frame = cp::seal_interactive(&session.ks, &session.riv, id, wseq, &c)?;
+                Self::submit_cp_frame(link, &mut out_q, &frame)?;
+                sent += 1;
+                // Navarro's reference transaction is reply-lockstep: the next operation follows
+                // the matching authenticated counter immediately. A generic burst drain adds an
+                // empty 10-ms read after every acknowledgment and changes the EP0/EP02 ordering.
+                let d = if profile.protocol.reply_discipline == profile::ReplyDiscipline::Lockstep {
+                    Self::lockstep_reply(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        cp_ctr,
+                        edid_out,
+                    )
+                } else {
+                    Self::drain_ep84(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        edid_out,
+                        Delta::from_millis(10),
+                    )
+                };
+                drained += d.reads;
+                acks += d.acks;
+                rejects += d.rejects;
+                cp_ctr += 1;
+                wseq += 2; // every initialization message is 32 B = 2 AES blocks
+            }};
+        }
+        // See `DockProfile::dock_wide_init`: a dock that does not expect these is left every
+        // later inner counter and AES block out of step by them.
+        if profile.protocol.dock_wide_init {
+            send_init!(0x0014, 0x0030, &[]);
+            send_init!(0x0015, 0x000b, &[0x01]);
+        }
+
+        if profile.protocol.video_commit_point == profile::VideoCommitPoint::BeforeConnectorRecords
+        {
+            // The working DLM transaction places the video-engine transition at this exact
+            // authenticated boundary: after the reply to 0x15/0x0b (counter 11), before the four
+            // connector-selecting 0x16/0x2a records (counters 12..15). Measured submit times are
+            // EP08 clear, +12.647 ms EP0a clear, +143 us vendor commit, +2.941 ms first 0x16/0x2a.
+            // Performing the same requests after finalization moved them 53 messages later.
+            link.clear_video_halt_wire(0)?;
+            fsleep(Delta::from_millis(13));
+            link.clear_video_halt_wire(1)?;
+            link.control_send(
+                0x24,
+                0x40, /* VENDOR_OUT */
+                0,
+                0,
+                &[],
+                timeout(),
+                GFP_KERNEL,
+            )?;
+            let mut state2 = [0u8; 28];
+            link.control_recv(0x22, 0xc1, 1, 0, &mut state2, timeout(), GFP_KERNEL)?;
+            fsleep(Delta::from_millis(3));
+        }
+        if profile.protocol.dock_wide_init {
+            for connector in 0..connector_count {
+                let prefix = [connector as u8, 0x01];
+                send_init!(0x0016, 0x002a, &prefix);
+            }
+        }
+
+        // Drain pending replies before starting the per-connector authentication blocks. Each block
+        // mirrors the HDCP AKE layout and ends by opening that connector's stream.
+        {
+            let d = Self::drain_ep84(
+                link,
+                ep84_q.as_mut(),
+                &mut resp,
+                session,
+                edid_out,
+                Delta::from_millis(10),
+            );
+            drained += d.reads;
+            acks += d.acks;
+            rejects += d.rejects;
+            if let Some(c) = d.display_cap_ctr {
+                for h in 0..Self::CP_SETUP_CONNECTORS {
+                    if stream_open_ctr[h] == Some(c) {
+                        connectors_present[h] = true;
+                    }
+                }
+            }
+        }
+        // Which connectors completed their downstream authentication. A connector with nothing
+        // plugged into it never runs one, so this is not expected to be all of them.
+        let mut connector_ok = [false; Self::CP_SETUP_CONNECTORS];
+        let mut heads_authenticated = 0usize;
+        'per_head: for connector in 0..connector_count {
+            // The socket number printed on the dock's case; the wire counts connectors from zero.
+            let socket = connector + 1;
+            // Derive an independent HDCP 2.2 authentication chain for this downstream connector.
+            let mut rtx_h = [0u8; drm_hdcp::RTX_LEN];
+            rng::fill(&mut rtx_h);
+            let mut km_h =
+                kernel::crypto::Secret::<{ drm_hdcp::ENCRYPTED_SESSION_KEY_LEN }>::zeroed();
+            rng::fill(&mut km_h[..]);
+            let mut rn_h = [0u8; drm_hdcp::RN_LEN];
+            rng::fill(&mut rn_h);
+            let mut ske_ks_h =
+                kernel::crypto::Secret::<{ drm_hdcp::ENCRYPTED_SESSION_KEY_LEN }>::zeroed();
+            rng::fill(&mut ske_ks_h[..]);
+            let mut riv_h = [0u8; drm_hdcp::RIV_LEN];
+            rng::fill(&mut riv_h);
+            let ekpub_h = hdcp::oaep_encrypt_km(&mut session.rsa, &km_h)?;
+            let mut kd_h: Option<kernel::crypto::Secret<32>> = None;
+            let mut edkey_h = None;
+            let mut v_h = None;
+            let mut fresh_rrx: Option<[u8; drm_hdcp::RRX_LEN]> = None;
+            let mut per_connector_repeater: Option<bool> = None;
+            let mut rrx_applied = false;
+            // SKE_Send_Eks establishes this connector's video key. Store the whitened key and the
+            // video nonce derived from the delivered RIV for the scanout arm burst. Layout: key(16)
+            // || nonce(8) || pad(8).
+            let stream_id = profile.geometry().stream_id(connector as u8);
+            video_keys[connector] = kernel::crypto::Secret::zeroed();
+            // Whether the dock applies the control-plane whitening constant to a per-connector SKE
+            // key is proven only for the link stream; the per-connector rule is carried over from
+            // Ridge, and both docks accept the sealed records it produces.
+            let video_key = cp::cp_session_key(&ske_ks_h);
+            video_keys[connector][..16].copy_from_slice(&video_key[..]);
+            let vnonce = cp::stream_content_nonce(&riv_h, stream_id);
+            video_keys[connector][16..24].copy_from_slice(&vnonce);
+            for (i, (id, sub, content_len)) in cp::CP_SETUP_PER_HEAD.iter().copied().enumerate() {
+                // The per-connector `rrx` arrives with the response to AKE_No_Stored_km. It is
+                // mandatory for deriving this connector's kd and Edkey before the consuming
+                // messages. V is not computed until the connector's own ReceiverID_List/V' has been
+                // received and verified.
+                if i >= 3 && !rrx_applied {
+                    let Some(rrx_h) = fresh_rrx else {
+                        // No `rrx` means this connector never began a downstream authentication,
+                        // which is what an empty DisplayPort connector looks like -- DLM does not
+                        // run a per-connector burst for a connector with no sink either, as a
+                        // capture of it driving a monitorless dock shows: one AKE for the dock,
+                        // none per connector.
+                        //
+                        // Skip the connector rather than failing the device. Aborting here took the
+                        // whole dock down whenever a single connector was empty, so a two-connector
+                        // dock with one monitor never came up at all, and a dock with none was
+                        // unreachable even for EDID and hotplug.
+                        vino_debug!(
+                            "vino: socket {socket} has no downstream sink (no AKE_Send_Rrx); skipping its authentication\n"
+                        );
+                        Self::announce_stream(link, &mut out_q, profile, connector)?;
+                        continue 'per_head;
+                    };
+                    let kd = hdcp::derive_kd(&km_h, &rtx_h, &rrx_h)?;
+                    edkey_h = Some(hdcp::compute_eks(&km_h, &rtx_h, &rrx_h, &rn_h, &ske_ks_h)?);
+                    // Ridge retains the older reply-drain path and has only the dock-wide list
+                    // available here. Navarro replaces this after SKE with the verified list from
+                    // this exact connector.
+                    if !profile.protocol.per_connector_onehot {
+                        let vf = hdcp::compute_v_full(&kd, &session.rxid_list);
+                        let mut ack = [0u8; drm_hdcp::V_PRIME_HALF_LEN];
+                        ack.copy_from_slice(&vf[drm_hdcp::V_PRIME_HALF_LEN..]);
+                        v_h = Some(ack);
+                    }
+                    kd_h = Some(kd);
+                    rrx_applied = true;
+                }
+                // id=0x26 (Stream_Manage restatement) is fully decoded -- deterministic content,
+                // not the generic path below. See `cp::stream_manage_restatement`'s doc comment.
+                if id == 0x0026 {
+                    let content = cp::stream_manage_restatement(
+                        cp_ctr,
+                        connector as u8,
+                        stream_id,
+                        profile.protocol.per_connector_onehot,
+                    )?;
+                    let frame =
+                        cp::seal_interactive(&session.ks, &session.riv, id, wseq, &content)?;
+                    Self::submit_cp_frame(link, &mut out_q, &frame)?;
+                    sent += 1;
+                    let d = if profile.protocol.per_connector_onehot {
+                        Self::wait_per_connector_push(
+                            link,
+                            ep84_q.as_mut(),
+                            &mut resp,
+                            session,
+                            ake::id::REPEATERAUTH_STREAM_READY,
+                            Delta::from_millis(30),
+                        )
+                    } else {
+                        Self::drain_ep84(
+                            link,
+                            ep84_q.as_mut(),
+                            &mut resp,
+                            session,
+                            edid_out,
+                            Delta::from_millis(10),
+                        )
+                    };
+                    drained += d.reads;
+                    acks += d.acks;
+                    rejects += d.rejects;
+                    fresh_rrx = fresh_rrx.or(d.per_connector_rrx);
+                    if profile.protocol.per_connector_onehot && d.per_connector_mprime.is_none() {
+                        pr_err!(
+                            "vino: socket {socket} downstream HDCP never returned M'/Stream_Ready\n"
+                        );
+                        return Err(EPROTO);
+                    }
+                    cp_ctr += 1;
+                    wseq += ((content_len + 15) / 16) as u32;
+                    // The vendor names the connector's content stream here, between the HDCP
+                    // restatement and the stream-open control record. The position is part of the
+                    // sequence: carried ahead of the first frame instead, this dock stops
+                    // answering altogether.
+                    Self::announce_stream(link, &mut out_q, profile, connector)?;
+                    continue;
+                }
+                let mut c = KVec::from_elem(0u8, content_len, GFP_KERNEL)?;
+                // Shared header (id / sub=0x10 / inner counter), identical to the plaintext AKE
+                // body layout (`ake::body`). The buffer is already zeroed by `from_elem`.
+                c[0..2].copy_from_slice(&id.to_le_bytes());
+                c[2..4].copy_from_slice(&sub.to_le_bytes());
+                c[4..6].copy_from_slice(&cp_ctr.to_le_bytes());
+                // Per-connector AKE messages carry the platform-specific connector marker, HDCP
+                // message id at offset 27 and the standard HDCP payload at offset 28.
+                match i {
+                    // AKE restatements: connector marker @23, HDCP msg-id tag @27, HDCP field @28..
+                    0 | 1 | 2 | 3 | 4 | 5 => {
+                        cp::connector_marker(
+                            &mut c,
+                            connector as u8,
+                            profile.protocol.per_connector_onehot,
+                        );
+                        c[27] = match i {
+                            0 => 0x02, // AKE_Init (rtx)
+                            1 => 0x13, // AKE_Transmitter_Info
+                            2 => 0x04, // AKE_No_Stored_km (Ekpub)
+                            3 => 0x09, // LC_Init (rn)
+                            4 => 0x0b, // SKE_Send_Eks (edkey+riv)
+                            _ => 0x0f, // 5: RepeaterAuth_Send_Ack (V)
+                        };
+                        match i {
+                            0 => {
+                                // AKE_Init carries Rtx and a fresh proprietary suffix.
+                                c[28..36].copy_from_slice(&rtx_h);
+                                rng::fill(&mut c[36..48]);
+                            }
+                            1 => {
+                                c[28..33].copy_from_slice(&[0x00, 0x06, 0x02, 0x00, 0x02]);
+                                rng::fill(&mut c[33..48]);
+                            }
+                            2 => {
+                                c[28..156].copy_from_slice(&ekpub_h);
+                                rng::fill(&mut c[156..160]);
+                            }
+                            3 => {
+                                c[28..36].copy_from_slice(&rn_h); // LC_Init: rn
+                                rng::fill(&mut c[36..48]);
+                            }
+                            4 => {
+                                let Some(ed) = edkey_h.as_ref() else {
+                                    return Err(EPROTO);
+                                };
+                                c[28..44].copy_from_slice(ed);
+                                c[44..52].copy_from_slice(&riv_h);
+                                rng::fill(&mut c[52..64]);
+                            }
+                            _ => {
+                                let Some(v) = v_h else {
+                                    return Err(EPROTO);
+                                };
+                                c[28..44].copy_from_slice(&v); // RepeaterAuth_Send_Ack: V
+                                rng::fill(&mut c[44..48]);
+                            }
+                        }
+                    }
+                    // Stream-open control: header + zero[8..22] + 10 host-random bytes[22..32]; no
+                    // connector marker, no tag (confirmed genuinely fully random across both
+                    // connectors). Record this connector's request counter. The display-capability
+                    // reply echoes it only when this connector has a monitor.
+                    7 => {
+                        if connector < stream_open_ctr.len() {
+                            stream_open_ctr[connector] = Some(cp_ctr);
+                        }
+                        rng::fill(&mut c[22..]);
+                    }
+                    // strm2: connector index @22, then the `<marker> [connector*4] 04` triple
+                    // @24..27, then a fresh 5-byte host-random tail. The marker is a per-platform
+                    // constant, not a connector count: Ridge sends 0x06 and Navarro 0x0c for two
+                    // and four connectors, but DL-3x00 sends 0x10 with two.
+                    8 => {
+                        c[22] = connector as u8;
+                        c[24] = profile.protocol.strm2_marker;
+                        c[25] = (connector as u8) * 4;
+                        c[26] = 0x04;
+                        rng::fill(&mut c[27..]);
+                    }
+                    _ => {}
+                }
+                let send_at = Instant::<Monotonic>::now();
+                let frame = cp::seal_interactive(&session.ks, &session.riv, id, wseq, &c)?;
+                Self::submit_cp_frame(link, &mut out_q, &frame)?;
+                sent += 1;
+                let mut d = if profile.protocol.per_connector_onehot && i <= 5 {
+                    let want = match i {
+                        0 => ake::id::AKE_SEND_CERT,
+                        1 => 0x14, // DisplayLink AKE_Receiver_Info
+                        2 => ake::id::AKE_SEND_RRX,
+                        3 => ake::id::LC_SEND_L_PRIME,
+                        4 => ake::id::REPEATERAUTH_SEND_RECEIVERID_LIST,
+                        _ => ake::id::RECEIVER_AUTH_STATUS,
+                    };
+                    Self::wait_per_connector_push(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        want,
+                        Delta::from_millis(30),
+                    )
+                } else if profile.protocol.per_connector_onehot {
+                    Self::lockstep_reply(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        cp_ctr,
+                        edid_out,
+                    )
+                } else {
+                    Self::drain_ep84(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        edid_out,
+                        Delta::from_millis(10),
+                    )
+                };
+                per_connector_repeater = per_connector_repeater.or(d.per_connector_repeater);
+                fresh_rrx = fresh_rrx.or(d.per_connector_rrx);
+
+                // AKE_No_Stored_km starts the receiver's H' calculation. Rrx is the immediate
+                // result; H' and pairing info are later milestones, and DLM sends no LC_Init
+                // (i == 3) until both have crossed EP84. Both platforms need the wait and the
+                // drain, or the connector authenticates on material that never arrived.
+                if i == 2 && !profile.protocol.per_connector_onehot {
+                    hold_until(send_at, HDCP_HPRIME_WAIT_US);
+                    // Wait for the rrx rather than sampling for it. A fixed drain window returns
+                    // whatever has already arrived, so a connector whose receiver answers a little
+                    // late reads as a connector with no sink and loses the whole rest of its burst
+                    // -- including the key exchange that gives the dock a key for its content
+                    // stream. How long a receiver may take to answer is a property of the dock,
+                    // so the bound comes from its profile.
+                    let dh = Self::wait_per_connector_push(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        ake::id::AKE_SEND_RRX,
+                        Delta::from_millis(profile.protocol.perhead_rrx_wait_ms),
+                    );
+                    fresh_rrx = fresh_rrx.or(dh.per_connector_rrx);
+                    per_connector_repeater = per_connector_repeater.or(dh.per_connector_repeater);
+                    d.add(dh);
+                }
+                if i == 2 && profile.protocol.per_connector_onehot {
+                    let Some(rrx_h) = fresh_rrx else {
+                        cp_ctr += 1;
+                        wseq += ((content_len + 15) / 16) as u32;
+                        vino_debug!(
+                            "vino: socket {socket} has no downstream sink (no AKE_Send_Rrx); skipping its authentication\n"
+                        );
+                        Self::announce_stream(link, &mut out_q, profile, connector)?;
+                        continue 'per_head;
+                    };
+                    hold_until(send_at, HDCP_HPRIME_WAIT_US);
+                    let dh = Self::wait_per_connector_push(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        ake::id::AKE_SEND_H_PRIME,
+                        Delta::from_millis(50),
+                    );
+                    d.add(dh);
+                    let dp = Self::wait_per_connector_push(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        0x08, // AKE_Send_Pairing_Info
+                        Delta::from_millis(30),
+                    );
+                    d.add(dp);
+                    let Some(hprime) = d.per_connector_hprime else {
+                        pr_err!(
+                            "vino: socket {socket} downstream HDCP returned no H'\n",
+                            socket = connector + 1
+                        );
+                        return Err(EPROTO);
+                    };
+                    let kd = hdcp::derive_kd(&km_h, &rtx_h, &rrx_h)?;
+                    let want_h =
+                        hdcp::compute_h(&kd, &rtx_h, per_connector_repeater.unwrap_or(true));
+                    if want_h != hprime {
+                        pr_err!(
+                            "vino: socket {socket} downstream H' mismatch\n",
+                            socket = connector + 1
+                        );
+                        return Err(EPROTO);
+                    }
+                    edkey_h = Some(hdcp::compute_eks(&km_h, &rtx_h, &rrx_h, &rn_h, &ske_ks_h)?);
+                    kd_h = Some(kd);
+                    rrx_applied = true;
+                    vino_debug!(
+                        "vino: socket {socket} downstream H' verified\n",
+                        socket = connector + 1
+                    );
+                }
+
+                if i == 3 && profile.protocol.per_connector_onehot {
+                    let Some(lprime) = d.per_connector_lprime else {
+                        pr_err!(
+                            "vino: socket {socket} downstream HDCP returned no L'\n",
+                            socket = connector + 1
+                        );
+                        return Err(EPROTO);
+                    };
+                    let (Some(kd), Some(rrx_h)) = (kd_h.as_ref(), fresh_rrx.as_ref()) else {
+                        return Err(EPROTO);
+                    };
+                    if hdcp::compute_l(kd, rrx_h, &rn_h) != lprime {
+                        pr_err!(
+                            "vino: socket {socket} downstream L' mismatch\n",
+                            socket = connector + 1
+                        );
+                        return Err(EPROTO);
+                    }
+                    vino_debug!(
+                        "vino: socket {socket} downstream L' verified\n",
+                        socket = connector + 1
+                    );
+                }
+
+                if i == 4 && profile.protocol.per_connector_onehot {
+                    let Some((list_header, vprime)) = d.per_connector_v else {
+                        pr_err!(
+                            "vino: socket {socket} downstream HDCP returned no ReceiverID_List/V'\n"
+                        );
+                        return Err(EPROTO);
+                    };
+                    let Some(kd) = kd_h.as_ref() else {
+                        return Err(EPROTO);
+                    };
+                    let vf = hdcp::compute_v_full(kd, &list_header);
+                    if vf[..drm_hdcp::V_PRIME_HALF_LEN] != vprime {
+                        pr_err!(
+                            "vino: socket {socket} downstream V' mismatch\n",
+                            socket = connector + 1
+                        );
+                        return Err(EPROTO);
+                    }
+                    let mut ack = [0u8; drm_hdcp::V_PRIME_HALF_LEN];
+                    ack.copy_from_slice(&vf[drm_hdcp::V_PRIME_HALF_LEN..]);
+                    v_h = Some(ack);
+                    if session.rxid_list.as_slice() != list_header {
+                        vino_debug!(
+                            "vino: socket {socket} ReceiverID list differs from dock-wide list\n",
+                            socket = connector + 1
+                        );
+                    }
+                    vino_debug!(
+                        "vino: socket {socket} downstream V' verified\n",
+                        socket = connector + 1
+                    );
+                }
+
+                if i == 5 && profile.protocol.per_connector_onehot {
+                    let Some(status) = d.per_connector_auth_status else {
+                        pr_err!(
+                            "vino: socket {socket} downstream HDCP returned no receiver-auth status\n"
+                        );
+                        return Err(EPROTO);
+                    };
+                    if status != 0x04 {
+                        pr_err!(
+                            "vino: socket {socket} downstream receiver-auth status {status:#x}, expected 0x04\n"
+                        );
+                        return Err(EPROTO);
+                    }
+                }
+                drained += d.reads;
+                acks += d.acks;
+                rejects += d.rejects;
+                // Attribute a display-capability reply by its echoed stream-open counter.
+                if let Some(c) = d.display_cap_ctr {
+                    for h in 0..Self::CP_SETUP_CONNECTORS {
+                        if stream_open_ctr[h] == Some(c) {
+                            connectors_present[h] = true;
+                        }
+                    }
+                }
+                cp_ctr += 1;
+                wseq += ((content_len + 15) / 16) as u32;
+            }
+            // Collect replies before moving to the next connector without adding another phase
+            // delay.
+            {
+                let d = Self::drain_ep84(
+                    link,
+                    ep84_q.as_mut(),
+                    &mut resp,
+                    session,
+                    edid_out,
+                    Delta::from_millis(10),
+                );
+                drained += d.reads;
+                acks += d.acks;
+                rejects += d.rejects;
+                if let Some(c) = d.display_cap_ctr {
+                    for h in 0..Self::CP_SETUP_CONNECTORS {
+                        if stream_open_ctr[h] == Some(c) {
+                            connectors_present[h] = true;
+                        }
+                    }
+                }
+            }
+
+            if trace_crypto_enabled() {
+                pr_info!(
+                    "vino-crypto: video connector={connector} raw_key={:02x?} delivered_riv={riv_h:02x?} key={:02x?} nonce={:02x?}\n",
+                    &ske_ks_h[..],
+                    &video_keys[connector][..16],
+                    &video_keys[connector][16..24]
+                );
+            }
+            connector_ok[connector] = true;
+            heads_authenticated += 1;
+        }
+        vino_debug!(
+            "vino: {heads_authenticated}/{} connector(s) authenticated\n",
+            connector_count
+        );
+
+        // Navarro performs one dock-wide state transition after the last per-connector AKE and
+        // before any connector finalizer. This message was absent from vino even though its
+        // authenticated DLM reply reports state 2. Keep it Navarro-only until a Ridge transcript
+        // establishes that platform's behavior.
+        if profile.protocol.per_connector_onehot {
+            let state = cp::post_auth_state_req(cp_ctr)?;
+            let frame = cp::seal_interactive(&session.ks, &session.riv, 0x15, wseq, &state)?;
+            Self::submit_cp_frame(link, &mut out_q, &frame)?;
+            sent += 1;
+            let d = Self::drain_ep84(
+                link,
+                ep84_q.as_mut(),
+                &mut resp,
+                session,
+                edid_out,
+                Delta::from_millis(10),
+            );
+            drained += d.reads;
+            acks += d.acks;
+            rejects += d.rejects;
+            cp_ctr += 1;
+            wseq += ((state.len() + 15) / 16) as u32;
+        }
+
+        // Finalize the streams of the connectors that authenticated, before entering the
+        // steady-state heartbeat.
+        //
+        // Only those connectors: finalizing a stream whose downstream authentication never ran
+        // makes the dock hard-reset a few seconds later and re-enumerate, which reads as a
+        // spontaneous dock reset rather than as a message it refused. The sequence is per
+        // connector, so it follows the dock's connector count rather than a fixed pair: a
+        // four-connector dock finalizes four, and DLM does the same. A dock that shares its control
+        // pipe is never finalized: DLM sends neither `0x16/0x4c` nor `0x15/0x4a` to it in a whole
+        // session, and every message it has not been asked to handle is one more it must answer on
+        // the pipe it is about to take pixels on.
+        let finalize = (0..connector_count)
+            .filter(|_| !profile.topology.video_on_ctrl_pipe)
+            .flat_map(|c| {
+                cp::CP_SETUP_FINALIZE_STEPS
+                    .iter()
+                    .map(move |&(id, sub)| (id, sub, c as u8))
+            });
+        for (id, sub, off22) in finalize {
+            if (off22 as usize) < Self::CP_SETUP_CONNECTORS && !connector_ok[off22 as usize] {
+                continue;
+            }
+            // Offset 22 selects the connector or step; sub 0x4c also carries 1 at offset 23.
+            let mut c = [0u8; 32];
+            c[0..2].copy_from_slice(&id.to_le_bytes());
+            c[2..4].copy_from_slice(&sub.to_le_bytes());
+            c[4..6].copy_from_slice(&cp_ctr.to_le_bytes());
+            c[22] = off22;
+            if sub == 0x004c {
+                c[23] = 0x01;
+                rng::fill(&mut c[24..]);
+            } else {
+                rng::fill(&mut c[23..]);
+            }
+            let frame = cp::seal_interactive(&session.ks, &session.riv, id, wseq, &c)?;
+            Self::submit_cp_frame(link, &mut out_q, &frame)?;
+            sent += 1;
+            let d = Self::drain_ep84(
+                link,
+                ep84_q.as_mut(),
+                &mut resp,
+                session,
+                edid_out,
+                Delta::from_millis(10),
+            );
+            drained += d.reads;
+            acks += d.acks;
+            rejects += d.rejects;
+            cp_ctr += 1;
+            wseq += 2; // 32 B content = 2 AES blocks
+        }
+        if let Some(queue) = out_q.as_mut() {
+            // A flush timeout is not fatal: `reap()` leaves a slow slot posted for a later call,
+            // and the session is otherwise complete. A dock with an empty connector never drains
+            // that connector's last EP02 write, which would otherwise fail the whole setup.
+            if let Err(e) = queue.flush(link.io(), timeout()) {
+                vino_debug!(
+                    "vino: EP02 queue flush timed out ({e:?}); session already acknowledged, continuing\n"
+                );
+            }
+        }
+
+        // Ridge commits after finalization. Navarro has already committed at its measured
+        // post-0x15/pre-0x16 boundary above.
+        if profile.protocol.video_commit_point == profile::VideoCommitPoint::AfterFinalize {
+            link.control_send(
+                0x24,
+                0x40, /* VENDOR_OUT */
+                0,
+                0,
+                &[],
+                timeout(),
+                GFP_KERNEL,
+            )?;
+            // Refresh the interface state after the render/commit request.
+            let mut state2 = [0u8; 28];
+            link.control_recv(0x22, 0xc1, 1, 0, &mut state2, timeout(), GFP_KERNEL)?;
+        }
+
+        // Read the dock's reply: a VERIFIED `wsub=0x45` ack means the cipher engaged on our frame.
+        let ls = Self::lockstep_reply(link, ep84_q.as_mut(), &mut resp, session, 0x08, edid_out);
+        drained += ls.reads;
+        acks += ls.acks;
+        rejects += ls.rejects;
+
+        const MAX_ROUNDS: usize = 16;
+        for _ in 0..MAX_ROUNDS {
+            let d = Self::drain_ep84(
+                link,
+                ep84_q.as_mut(),
+                &mut resp,
+                session,
+                edid_out,
+                Delta::from_millis(10),
+            );
+            drained += d.reads;
+            acks += d.acks;
+            rejects += d.rejects;
+            if d.reads == 0 {
+                break;
+            }
+        }
+
+        if acks == 0 {
+            pr_err!(
+                "vino: encrypted session not acknowledged (reads={drained}, rejects={rejects})\n"
+            );
+            return Err(EPROTO);
+        }
+
+        // Complete downstream discovery on the authenticated counter stream.
+        if profile.protocol.per_connector_onehot {
+            // Navarro's authenticated DLM transcript is a compact, ordered transaction. Keep it
+            // separate from Ridge's older retry-heavy discovery below: hundreds of extra status
+            // polls delayed Navarro's first mode by ~23 seconds and changed every live counter.
+            macro_rules! navarro_send {
+                ($id:expr, $body:expr) => {{
+                    let id: u16 = $id;
+                    let body = $body;
+                    let e = Self::send_live_cp(
+                        link,
+                        session,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        edid_out,
+                        id,
+                        wseq,
+                        &body,
+                    )?;
+                    drained += e.reads;
+                    acks += e.acks;
+                    rejects += e.rejects;
+                    sent += 1;
+                    wseq = wseq.wrapping_add(((body.len() + 15) / 16) as u32);
+                    cp_ctr += 1;
+                }};
+            }
+
+            // DLM first seeks every physical connector, including empty sockets.
+            for connector in 0..connector_count {
+                let probe = cp::get_edid_req_sub(cp_ctr, 0x20, connector as u8)?;
+                navarro_send!(0x15, probe);
+            }
+            let devq = cp::device_query_req(cp_ctr, 0x0000)?;
+            navarro_send!(0x14, devq);
+
+            let mut active = [false; Self::CP_SETUP_CONNECTORS];
+            for connector in 0..connector_count {
+                // Navarro exposes four connector numbers on two physical video pipes, and the
+                // reference DLM session opened only the first connector on each pipe -- but that
+                // session had its two panels in sockets 1 and 2. Sockets 3 and 4 are not aliases
+                // of them: they are separate physical connectors that happen to share a bulk
+                // endpoint, with their own selector, EDID and stream. Skipping them by endpoint
+                // made a monitor in socket 3 or 4 invisible, with the dock never even probed for
+                // it. Read every socket; engagement below is what stays selective.
+                active[connector] = true;
+                *edid_out = None;
+                let hu8 = connector as u8;
+                let kick = cp::edid_readiness_kick(cp_ctr, hu8)?;
+                navarro_send!(0x16, kick);
+                let probe = cp::get_edid_req_sub(cp_ctr, 0x20, hu8)?;
+                navarro_send!(0x15, probe);
+                let fetch = cp::get_edid_req(cp_ctr, hu8)?;
+                navarro_send!(0x15, fetch);
+                // The fetch drain carries the asynchronous EDID in the working DLM cadence.
+                edid_connectors[connector] = edid_out.take();
+                discovery_deferred[connector] = edid_connectors[connector].is_none();
+            }
+            // Engage each connector that answered with an EDID, once, after all kick/probe/fetch
+            // triplets. Gated on a recovered EDID because that is the presence signal on this
+            // platform, and because driving setup at a socket with nothing in it is exactly what
+            // makes this dock hard-reset a few seconds later.
+            for connector in 0..connector_count {
+                if active[connector] && edid_connectors[connector].is_some() {
+                    let engage = cp::edid_engage_req(cp_ctr, connector as u8)?;
+                    navarro_send!(0x16, engage);
+                }
+            }
+
+            // Two status samples bracket the one-shot RTC synchronization, followed by thirteen
+            // more samples in the same-day working capture.
+            for _ in 0..2 {
+                let status = cp::device_query_req(cp_ctr, 0x000c)?;
+                navarro_send!(0x14, status);
+            }
+            let now = kernel::time::ktime_get_real_seconds();
+            let rtc = cp::rtc_sync_req(
+                cp_ctr,
+                now,
+                *crate::module_parameters::rtc_utc_offset_minutes.value(),
+            )?;
+            navarro_send!(0x1e, rtc);
+            for _ in 0..13 {
+                let status = cp::device_query_req(cp_ctr, 0x000c)?;
+                navarro_send!(0x14, status);
+            }
+            // The last discovery records immediately preceding DLM's clear-mode pair re-seek
+            // each active connector once.
+            for connector in 0..connector_count {
+                if active[connector] {
+                    let probe = cp::get_edid_req_sub(cp_ctr, 0x20, connector as u8)?;
+                    navarro_send!(0x15, probe);
+                }
+            }
+        } else if profile.topology.video_on_ctrl_pipe {
+            // Discovery on a dock that shares its control pipe walks all its connectors through
+            // each phase before starting the next, rather than taking one connector end to end.
+            // Running a connector to completion first leaves the connector that went first without
+            // an EDID while the second streams, which is what a single-monitor dock looks like from
+            // userspace.
+            //
+            // It is also short: no reader kick, one engage rather than two, and no readiness
+            // polling. Every extra transaction here is one the dock has to answer on the pipe it
+            // will shortly be asked to take pixels on.
+            macro_rules! walk_send {
+                ($id:expr, $body:expr) => {{
+                    let id: u16 = $id;
+                    let body = $body;
+                    let e = Self::send_live_cp(
+                        link,
+                        session,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        edid_out,
+                        id,
+                        wseq,
+                        &body,
+                    )?;
+                    drained += e.reads;
+                    acks += e.acks;
+                    rejects += e.rejects;
+                    sent += 1;
+                    wseq = wseq.wrapping_add(((body.len() + 15) / 16) as u32);
+                    cp_ctr += 1;
+                }};
+            }
+
+            for connector in 0..connector_count {
+                let hu8 = connector as u8;
+                *edid_out = None;
+                let probe = cp::get_edid_req_sub(cp_ctr, 0x20, hu8)?;
+                walk_send!(0x15, probe);
+                let fetch = cp::get_edid_req(cp_ctr, hu8)?;
+                walk_send!(0x15, fetch);
+                // The EDID arrives asynchronously, a few messages behind the fetch it answers, and
+                // the push names no connector -- so a connector's answer has to be collected before
+                // the next connector is asked, even though DLM issues both fetches back to back.
+                let waited = Instant::<Monotonic>::now();
+                while edid_out.is_none() && Instant::<Monotonic>::now() - waited < EDID_REPLY_WAIT {
+                    let d = Self::drain_ep84(
+                        link,
+                        ep84_q.as_mut(),
+                        &mut resp,
+                        session,
+                        edid_out,
+                        Delta::from_millis(20),
+                    );
+                    drained += d.reads;
+                    acks += d.acks;
+                    rejects += d.rejects;
+                }
+                edid_connectors[connector] = edid_out.take();
+                vino_debug!(
+                    "vino: socket {socket} EDID fetch {}\n",
+                    if edid_connectors[connector].is_some() {
+                        "succeeded"
+                    } else {
+                        "returned no EDID"
+                    },
+                    socket = connector + 1
+                );
+            }
+            // Both probes are answered before either sink is engaged, and the last message before
+            // the engages restates the session hello.
+            let hello = cp::session_hello(cp_ctr);
+            walk_send!(0x14, hello);
+            // Every connector, not only the ones that answered with an EDID. This dock reports no
+            // EDID for a sink it is nonetheless driving, so an EDID is evidence of presence and
+            // its absence is evidence of nothing; the vendor engages both connectors before any
+            // pixels and leaves an unoccupied one engaged for the life of the session.
+            for connector in 0..connector_count {
+                let engage = cp::edid_engage_req(cp_ctr, connector as u8)?;
+                walk_send!(0x16, engage);
+            }
+
+            // Open every connector's sealed video stream, and announce its video plane.
+            //
+            // This is where DLM does it: after the sinks are engaged, before the capability
+            // queries, and long before any mode is set. The sealed record takes block zero of the
+            // stream so the decoder configuration that follows it at prologue time takes block
+            // one; `set_video_keys` is told as much.
+            //
+            // Every connector, not only the ones that answered with an EDID: a monitor that arrives
+            // after setup would otherwise be driven on a stream the dock was never told about, and
+            // this dock has no video pipe to open one on later. The vendor opens both.
+            //
+            // A dock with a video pipe of its own is opened by the scanout path instead,
+            // immediately ahead of the frame that needs it -- it has a pipe to do that on.
+            // The vendor spaces the stages of this burst with status polls; see `SetupPolls`.
+            // They are round trips, so a stage that follows three of them is a stage the dock was
+            // given three acknowledged messages' worth of time to reach. Opening both streams back
+            // to back puts the same records on the wire and gives it none of that.
+            macro_rules! settle_polls {
+                ($n:expr) => {{
+                    for _ in 0..$n {
+                        let status = cp::device_query_req(cp_ctr, 0x000c)?;
+                        walk_send!(0x14, status);
+                    }
+                }};
+            }
+
+            for connector in 0..connector_count {
+                settle_polls!(profile.protocol.setup_polls.before_open(connector as u8));
+                let stream_id = profile.geometry().stream_id(connector as u8);
+                let mut vkey = kernel::crypto::Secret::<16>::zeroed();
+                vkey.copy_from_slice(&video_keys[connector][..16]);
+                let mut vnonce = [0u8; 8];
+                vnonce.copy_from_slice(&video_keys[connector][16..24]);
+                let content = cp::stream_open(profile.protocol.stream_marker_kind);
+                let open = cp::seal_video_arm(&vkey, &vnonce, stream_id, 0x000a, 0, &content)?;
+                link.ctrl_send(&open, timeout(), GFP_KERNEL)?;
+                let announce = cp::stream_announce(
+                    u16::from(profile.geometry().connector_selector(connector as u8)),
+                    0,
+                );
+                link.ctrl_send(&announce, timeout(), GFP_KERNEL)?;
+                sent += 2;
+                *stream_opened |= 1u32 << connector;
+                let d = Self::drain_ep84(
+                    link,
+                    ep84_q.as_mut(),
+                    &mut resp,
+                    session,
+                    edid_out,
+                    Delta::from_millis(10),
+                );
+                drained += d.reads;
+                acks += d.acks;
+                rejects += d.rejects;
+            }
+
+            settle_polls!(profile.protocol.setup_polls.after_stream_opens);
+
+            // Every connector again, for the same reason the engages are.
+            for connector in 0..connector_count {
+                let query = cp::post_edid_query(cp_ctr, connector as u8)?;
+                walk_send!(0x15, query);
+            }
+        } else {
+            // Open discovery with a heartbeat and the one-shot device-capability query.
+            let hb = cp::heartbeat(cp_ctr)?;
+            let e = Self::send_live_cp(
+                link,
+                session,
+                ep84_q.as_mut(),
+                &mut resp,
+                edid_out,
+                0x16,
+                wseq,
+                &hb,
+            )?;
+            drained += e.reads;
+            acks += e.acks;
+            rejects += e.rejects;
+            wseq = wseq.wrapping_add(((hb.len() + 15) / 16) as u32);
+            cp_ctr += 1;
+
+            let devq = cp::device_query_req(cp_ctr, 0x0000)?;
+            let e = Self::send_live_cp(
+                link,
+                session,
+                ep84_q.as_mut(),
+                &mut resp,
+                edid_out,
+                0x14,
+                wseq,
+                &devq,
+            )?;
+            drained += e.reads;
+            acks += e.acks;
+            rejects += e.rejects;
+            wseq = wseq.wrapping_add(((devq.len() + 15) / 16) as u32);
+            cp_ctr += 1;
+
+            // EDID discovery is a probe/kick/fetch sequence followed by two engage messages. A
+            // cold receiver then needs bounded status polling until the readiness bit is set.
+            const EDID_STEP_DELAY: Delta = Delta::from_millis(100);
+            const EDID_EARLY_ROUNDS: usize = 1;
+            // Bound both the poll count and wall-clock duration.
+            const EDID_POLL_ITERS: usize = 250;
+            const EDID_POLL_DELAY: Delta = Delta::from_millis(20);
+            const EDID_POLL_PROBE_EVERY: usize = 8;
+            // Offset 22 selects the downstream connector. A connector the display-capability
+            // transaction reported empty need not be probed, but that inference only holds once
+            // some connector has reported one: a dock that pushed no capability at all has said
+            // nothing about any socket, and treating silence as "empty" leaves every connector past
+            // the first undiscovered.
+            let capabilities_reported = connectors_present.iter().any(|&present| present);
+            for connector in 0..connector_count {
+                if connector != 0 && capabilities_reported && !connectors_present[connector] {
+                    continue;
+                }
+                let hu8 = connector as u8;
+                let socket = connector + 1;
+                *edid_out = None;
+                let mut edid_ready = false;
+                let mut transport_error = None;
+                'discovery: {
+                    macro_rules! edid_send {
+                        ($ep:expr, $body:expr, $tag:expr) => {{
+                            match Self::send_live_cp(
+                                link,
+                                session,
+                                ep84_q.as_mut(),
+                                &mut resp,
+                                edid_out,
+                                $ep,
+                                wseq,
+                                &$body,
+                            ) {
+                                Ok(e) => {
+                                    drained += e.reads;
+                                    acks += e.acks;
+                                    rejects += e.rejects;
+                                    wseq = wseq.wrapping_add((($body.len() + 15) / 16) as u32);
+                                    cp_ctr += 1;
+                                    edid_ready |= e.edid_ready;
+                                    vino_debug!(
+                                        "vino: live connector {} {} sent\n",
+                                        connector,
+                                        $tag
+                                    );
+                                }
+                                Err(e) => {
+                                    transport_error = Some(e);
+                                    break 'discovery;
+                                }
+                            }
+                        }};
+                    }
+                    // A block that arrives before the dock reports its downstream read complete
+                    // describes the dock's own bridge rather than the monitor, and publishing it
+                    // drives the panel at a timing it never advertised. Offset 26 bit 7 of the
+                    // presence reply is that report; drop anything offered ahead of it and let the
+                    // engage below produce the real one.
+                    let gate_on_ready = profile.quirks.edid_ready_reported;
+                    macro_rules! edid_settled {
+                        () => {{
+                            if gate_on_ready && !edid_ready && edid_out.is_some() {
+                                vino_debug!(
+                                    "vino: socket {socket} discarding an EDID offered before the \
+                                     downstream read completed\n"
+                                );
+                                *edid_out = None;
+                            }
+                            edid_out.is_some()
+                        }};
+                    }
+                    'early: for cycle in 0..EDID_EARLY_ROUNDS {
+                        if edid_settled!() {
+                            break;
+                        }
+                        vino_debug!(
+                            "vino: live get-EDID socket {socket} early round {cycle}\n",
+                            socket = connector + 1
+                        );
+                        for _ in 0..2 {
+                            let probe = cp::get_edid_req_sub(cp_ctr, 0x20, hu8)?;
+                            edid_send!(0x15, probe, "get-EDID probe (id=0x15 sub=0x20)");
+                            fsleep(EDID_STEP_DELAY);
+                        }
+                        // Start or continue the selected connector's downstream DDC read.
+                        let kick = cp::edid_readiness_kick(cp_ctr, hu8)?;
+                        edid_send!(0x16, kick, "get-EDID kick (id=0x16 sub=0x4b)");
+                        fsleep(EDID_STEP_DELAY);
+                        let req = cp::get_edid_req(cp_ctr, hu8)?;
+                        edid_send!(0x15, req, "get-EDID fetch (id=0x15 sub=0x21)");
+                        if edid_settled!() {
+                            break 'early;
+                        }
+                        fsleep(EDID_STEP_DELAY);
+                        // EDID arrives asynchronously after the fetch acknowledgment.
+                        let reply_wait = Instant::<Monotonic>::now();
+                        while Instant::<Monotonic>::now() - reply_wait < Delta::from_secs(2) {
+                            let d = Self::drain_ep84(
+                                link,
+                                ep84_q.as_mut(),
+                                &mut resp,
+                                session,
+                                edid_out,
+                                Delta::from_millis(20),
+                            );
+                            drained += d.reads;
+                            acks += d.acks;
+                            rejects += d.rejects;
+                            edid_ready |= d.edid_ready;
+                            if edid_settled!() {
+                                break 'early;
+                            }
+                        }
+                    }
+                    // Engage is required twice even if the EDID push arrived early.
+                    for _ in 0..2 {
+                        let engage = cp::edid_engage_req(cp_ctr, hu8)?;
+                        edid_send!(0x16, engage, "get-EDID engage (id=0x16 sub=0x0023)");
+                        fsleep(EDID_STEP_DELAY);
+                    }
+                    if edid_out.is_none() {
+                        // Bound wall-clock time independently of the iteration
+                        // count because each failed send has its own USB timeout.
+                        const EDID_POLL_MAX: Delta = Delta::from_secs(6);
+                        let poll_start = Instant::<Monotonic>::now();
+                        'poll: for i in 0..EDID_POLL_ITERS {
+                            if edid_out.is_some() || edid_ready {
+                                break 'poll;
+                            }
+                            if Instant::<Monotonic>::now() - poll_start > EDID_POLL_MAX {
+                                vino_debug!(
+                                "vino: get-EDID socket {socket} readiness poll hit wall-clock cap\n"
+                            );
+                                break 'poll;
+                            }
+                            let status = cp::device_query_req(cp_ctr, 0x000c)?;
+                            edid_send!(0x14, status, "device-status poll (id=0x14 sub=0x000c)");
+                            if i % EDID_POLL_PROBE_EVERY == EDID_POLL_PROBE_EVERY - 1 {
+                                let probe = cp::get_edid_req_sub(cp_ctr, 0x20, hu8)?;
+                                edid_send!(
+                                    0x15,
+                                    probe,
+                                    "get-EDID readiness probe (id=0x15 sub=0x20)"
+                                );
+                            }
+                            if edid_out.is_some() || edid_ready {
+                                break 'poll;
+                            }
+                            fsleep(EDID_POLL_DELAY);
+                        }
+                        vino_debug!(
+                        "vino: get-EDID socket {socket} readiness poll finished (ready={edid_ready})\n"
+                    );
+                        // The asynchronous `id=0x194` EDID can follow the fetch
+                        // acknowledgment by several messages.
+                        for _ in 0..24 {
+                            if edid_settled!() {
+                                break;
+                            }
+                            let req = cp::get_edid_req(cp_ctr, hu8)?;
+                            edid_send!(0x15, req, "get-EDID retry (id=0x15 sub=0x21)");
+                            let d = Self::drain_ep84(
+                                link,
+                                ep84_q.as_mut(),
+                                &mut resp,
+                                session,
+                                edid_out,
+                                Delta::from_millis(10),
+                            );
+                            drained += d.reads;
+                            acks += d.acks;
+                            rejects += d.rejects;
+                            fsleep(EDID_POLL_DELAY);
+                        }
+                    }
+                    // Complete this connector with its post-EDID capability query.
+                    let query = cp::post_edid_query(cp_ctr, hu8)?;
+                    edid_send!(0x15, query, "post-EDID capability query (id=0x15 sub=0x53)");
+                    // `edid_send!` folds the drain's readiness bit into `edid_ready`. This is the
+                    // last statement of the per-connector iteration and the next connector
+                    // re-derives it, so that update is deliberately not read again here.
+                    let _ = edid_ready;
+                }
+
+                discovery_deferred[connector] = transport_error.is_some();
+                if let Some(e) = transport_error {
+                    // The encrypted session is already authenticated. Keep it running and recover
+                    // this connector independently after a connector-local discovery timeout.
+                    *edid_out = None;
+                    pr_warn!(
+                        "vino: socket {socket} discovery timed out ({e:?}); deferring to runtime \
+                         recovery\n",
+                        socket = connector + 1
+                    );
+                }
+                edid_connectors[connector] = edid_out.take();
+                vino_debug!(
+                    "vino: socket {socket} EDID fetch {}\n",
+                    if edid_connectors[connector].is_some() {
+                        "succeeded"
+                    } else {
+                        "returned no EDID"
+                    },
+                    socket = connector + 1
+                );
+            }
+
+            // KMS is the sole owner of mode selection; setup only discovers connector state.
+        }
+
+        if rejects > 0 {
+            pr_warn!("vino: dock returned {rejects} undecryptable control frame(s)\n");
+        }
+        vino_debug!("vino: control setup tx={sent} rx={drained} ack={acks} reject={rejects}\n");
+        // Hand the caller the running counters: the next free AES-CTR block (`wseq`) and inner
+        // message counter (`cp_ctr`), so runtime KMS sends (mode-set/cursor) continue the sequence.
+        Ok((sent, wseq, cp_ctr))
+    }
+}