PCI/ASPM: Intel Battlemage (Arc Pro B70) bricks at boot when `pcie_aspm.policy=powersupersave` enables ASPM_L1.1 on AMD root port link

From: Pavel Shirshov

Date: Thu May 07 2026 - 18:14:54 EST

The report and the patch below are completely claude'd but the quirk in the patch works.

PCI/ASPM: Intel Battlemage (Arc Pro B70) bricks at boot when
pcie_aspm.policy=powersupersave enables ASPM_L1.1 on AMD root port link

================================================================
SUMMARY
================================================================

On Linux 7.0.3, an Intel Arc Pro B70 (Battlemage / BMG-G31, GPU PCI
ID 8086:e223) plugged into an AMD Ryzen 9 5950X system fails to wake
from D3cold during PCI core enumeration when the kernel is booted
with pcie_aspm.policy=powersupersave. The card is permanently
inaccessible until reboot with a different policy.
pcie_aspm.policy=powersave (L0s+L1, no substates) works correctly.

The failure surfaces in PCI core first; downstream xe driver bind
then fails with -EPROTO:

pcieport 0000:02:01.0: Unable to change power state from D3cold
to D0, device inaccessible
pcieport 0000:02:02.0: Unable to change power state from D3cold
to D0, device inaccessible
xe 0000:03:00.0: Unable to change power state from D3cold to D0,
device inaccessible
xe 0000:03:00.0: [drm] Running in SR-IOV VF mode
[misdetected: dead config space reads as 0xff]
xe 0000:03:00.0: [drm] *ERROR* VF: Tile0: GT0: Failed to reset
GuC state (-EPROTO)
xe 0000:03:00.0: probe with driver xe failed with error -71

After the brick, "lspci -vvv -s 03:00.0" reports
"!!! Unknown header type 7f" -- the canonical signature of a PCI
device whose config space reads return all-ones, i.e. the link to the
device is dead.

================================================================
HARDWARE
================================================================

CPU / root complex:
AMD Ryzen 9 5950X (Starship/Matisse). The root port hosting the
BMG card is 0000:00:01.1 -- "Advanced Micro Devices, Inc. [AMD]
Starship/Matisse GPP Bridge" (subsystem 1022:1453).

GPU:
Intel Arc Pro B70 -- 8086:e223 (BMG-G31, subsystem 8086:1701).

On-card topology -- the card has a two-layer on-board PCIe switch:
0000:01:00.0 Intel 8086:e2ff -- BMG card upstream switch port,
PCIe 5.0 x16 capable (currently
downgraded to Gen4 x16).
0000:02:01.0 Intel 8086:e2f0 -- BMG card downstream switch
port, PCIe Gen1 x1 internal.
0000:03:00.0 Intel 8086:e223 -- GPU endpoint, PCIe Gen1 x1
internal.

Other:
BIOS has PCIe ASPM enabled in firmware. pcie_aspm=force is NOT
set on the kernel command line. Motherboard: ASRock X570
(specifics in attached dmidecode.txt).

================================================================
REPRODUCER
================================================================

Boot any kernel >= 7.0 with kernel command line containing:

pcie_aspm.policy=powersupersave xe.force_probe=*

(Also reproduces under earlier 6.x kernels.)

Reverting the cmdline to "pcie_aspm.policy=powersave" and rebooting
restores the card. No firmware reset is required between attempts --
the brick is purely a runtime link-state failure during kernel boot.

================================================================
ASPM NEGOTIATION
================================================================

Captured with "lspci -vvv" on a working policy=powersave boot
(attached: 20260507-204348-powersave-7.0.3.tar.zst).

Link 1: 00:01.1 AMD root <-> 01:00.0 BMG upstream
Lower end (AMD root, L1SubCap):
PCI-PM_L1.2- PCI-PM_L1.1+ ASPM_L1.2- ASPM_L1.1+
Upper end (BMG upstream, L1SubCap):
PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
Active L1SubCtl1 under policy=powersave:
PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-

Link 2: 01:00.0 <-> 02:01.0 (card-internal switch)
No L1SS capability advertised on either end.

Link 3: 02:01.0 <-> 03:00.0 (card-internal to GPU)
No L1SS capability advertised on either end.

Conclusion: only Link 1 -- the platform-facing AMD<->BMG link -- is
L1SS-capable on both ends, and the intersection is ASPM_L1.1 only
(the AMD GPP root port advertises L1.1 but not L1.2). With
policy=powersupersave, the kernel arms ASPM_L1.1 on this link. After
that, every D3cold->D0 transition fails.

Both ends advertise multi-retimer support (Retimer+ 2Retimers+ on
the AMD root port and on the BMG upstream port). Retimers + L1SS
have a history of wake-recovery problems on other platforms; this
may be the same class of issue.

================================================================
TIMELINE -- failed boot, kernel 7.0.3
================================================================

Excerpted from dmesg-relevant.txt in the powersupersave capture:

28.792s pcieport 0000:00:01.1: PME: Signaling with IRQ 48
[AMD root port for BMG]
28.842s pcieport 0000:02:01.0: Unable to change power state from
D3cold to D0, device inaccessible
28.843s pcieport 0000:02:02.0: Unable to change power state from
D3cold to D0, device inaccessible
...
29.034s xe 0000:03:00.0: Unable to change power state from
D3cold to D0, device inaccessible
29.035s xe 0000:03:00.0: [drm] Running in SR-IOV VF mode
29.035s xe 0000:03:00.0: [drm] *ERROR* VF: Tile0: GT0: Failed
to reset GuC state (-EPROTO)
29.035s xe 0000:03:00.0: probe with driver xe failed with
error -71

The PCI core's first wake attempt at 28.842s (the immediate parent
bridge of the BMG GPU) fails before any driver probe runs. This
confirms the failure is in the PCI/ASPM layer, not in xe; xe just
sees the resulting dead config space and misclassifies the PF as a
VF.

================================================================
WORKING-POLICY LSPCI EXCERPTS (relevant capabilities)
================================================================

policy=powersave baseline, root port 00:01.1:

LnkCap: Speed 16GT/s, Width x16, ASPM L1, Exit Latency L1 <64us
LnkCtl: ASPM L1 Enabled
LnkSta: Speed 16GT/s, Width x16
Capabilities: [370 v1] L1 PM Substates
L1SubCap: PCI-PM_L1.2- PCI-PM_L1.1+ ASPM_L1.2- ASPM_L1.1+
L1_PM_Substates+
L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
L1SubCtl2:

policy=powersave baseline, BMG upstream 01:00.0:

LnkCap: Speed 32GT/s, Width x16, ASPM L1, Exit Latency L1 <32us
LnkCtl: ASPM L1 Enabled
LnkSta: Speed 16GT/s (downgraded), Width x16
Capabilities: [244 v1] L1 PM Substates
L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
L1_PM_Substates+
L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
L1SubCtl2: T_PwrOn=14us

================================================================
PROPOSED FIX
================================================================

Disable both L1SS substates on the BMG card's upstream switch port
(8086:e2ff) via a DECLARE_PCI_FIXUP_FINAL. Standard ASPM L1 still
applies, so the link still benefits from the deepest substate the
BMG silicon handles correctly. The quirk keys on the card upstream
port, which is shared across the BMG product family, so it covers
all current BMG SKUs without enumerating individual GPU-endpoint
IDs.

The patch is in the attached intel-bmg-disable-l1ss.patch. With the
patch applied, pcie_aspm.policy=powersupersave boots cleanly on this
hardware (verification in progress at time of report).

Empirical narrowing -- ASPM_L1.1 specifically is the trigger.

An intermediate version of the quirk passed only
PCIE_LINK_STATE_L1_1 | PCIE_LINK_STATE_L1_2 to
pci_disable_link_state(), leaving the PCI-PM substate bits armed.
After applying that variant, lspci reported

L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1+ ASPM_L1.2- ASPM_L1.1-

on the BMG upstream port -- i.e. only the two ASPM substate bits
were cleared, the PCI-PM substate bits stayed armed -- yet the
system booted, xe bound, and the GPU operated normally. Combined
with the AMD root port advertising only ASPM_L1.1+ (not L1.2),
this isolates ASPM_L1.1 as the specific bit whose activation
bricks the BMG card. The PCI-PM L1.x substates were also disabled
in the final patch for hygiene, but they are not load-bearing for
the fix on this hardware (the GPU does not enter D3hot during
normal operation, so PCI-PM substates are inert).

Remaining open questions for review:

1. Is the underlying defect in the AMD Starship root port (cannot
wake the link from ASPM_L1.1) or in the BMG e2ff upstream port
(cannot exit ASPM_L1.1 cleanly)? If the former, future BMG
cards on Intel platforms may not need this quirk; if the
latter, the quirk is correct for BMG everywhere. We do not
have a non-AMD reproducer to disambiguate.

2. Should the quirk also apply to the AMD Starship/Matisse GPP
Bridge itself (1022:1483 / 1022:1484-class IDs, see
lspci-nn.txt)? That would be a broader brushstroke but might
protect other devices presenting the same negotiation.

================================================================
WORKAROUND IN USE
================================================================

Until the quirk lands upstream, downstream users on this hardware
must boot with pcie_aspm.policy=powersave (or default), losing
~25 W of idle savings that the deeper substates would otherwise
provide.

================================================================
ATTACHMENTS
================================================================

Tarballs produced by debug/20260507-aspm-capture.sh:

20260507-204348-powersave-7.0.3.tar.zst
-- working baseline

20260507-205055-powersupersave-7.0.3.tar.zst
-- failed reproduction

Each tarball contains:

manifest.txt kernel, policy, hostname, GPU BDFs
cmdline.txt kernel command line
uname.txt kernel version
nixos.txt userspace metadata
dmidecode.txt BIOS/board info
lspci-tree.txt PCI topology
lspci-nn.txt PCI device list
lspci-vvv-all.txt full system lspci -vvv

gpu-03_00_0/ per-device captures for the GPU and
every PCI ancestor up to the root
complex:
lspci-vvv.txt GPU
parent-0-02_01_0.txt BMG card-internal downstream switch
parent-1-01_00_0.txt BMG card upstream port (e2ff)
parent-2-00_01_1.txt AMD root port
sysfs.txt selected sysfs attributes

dmesg-full.txt full kernel ring buffer
dmesg-relevant.txt filtered for PCI/xe/ASPM/L1
journal-kernel-current-boot.txt
journal-kernel-prev-boot.txt
drivers.txt xe / i915 driver state,
/sys/class/drm

Patch: intel-bmg-disable-l1ss.patch (attached separately)

NixOS 26.05 (nixpkgsRevision:
549bd84d6279f9852cae6225e372cc67fb91a4c1)

Kernel:
7.0.3 #1-NixOS SMP PREEMPT_DYNAMIC Thu Apr 30 09:13:05 UTC 2026

Attachment: 20260507-204348-powersave-7.0.3.tar.zst
Description: application/zstd

Attachment: 20260507-205055-powersupersave-7.0.3.tar.zst
Description: application/zstd

PCI/ASPM: disable L1.1/L1.2 substates for Intel Battlemage discrete GPU upstream port

Intel Battlemage (BMG-G21 / BMG-G31, e.g. Arc Pro B70) discrete GPU cards
expose a two-layer on-card PCIe switch:

AMD/Intel root port <-> 8086:e2ff (BMG card upstream)
8086:e2f0 (BMG card downstream)
8086:e22x (BMG GPU endpoint, e.g. e223 = Arc Pro B70)

The platform-facing link (root port <-> 8086:e2ff) is the only link in the
chain that advertises L1 PM Substates support on both ends. On AMD
Starship/Matisse (Ryzen 5xxx) root ports, the intersection is ASPM_L1.1
only (the AMD port advertises L1.1 but not L1.2). When pcie_aspm.policy=
powersupersave arms ASPM_L1.1 on this link, the BMG card cannot recover
from the resulting low-power state on subsequent D3cold->D0 transition,
leaving the device permanently inaccessible:

pcieport 0000:02:01.0: Unable to change power state from D3cold to D0, device inaccessible
xe 0000:03:00.0: Unable to change power state from D3cold to D0, device inaccessible
xe 0000:03:00.0: [drm] Running in SR-IOV VF mode [misdetected: dead config space]
xe 0000:03:00.0: [drm] *ERROR* VF: Tile0: GT0: Failed to reset GuC state (-EPROTO)
xe 0000:03:00.0: probe with driver xe failed with error -71

Reproduces deterministically on Linux 7.0.3 with an Arc Pro B70 in an
AMD Ryzen 9 5950X system. pcie_aspm.policy=powersave (L0s+L1 only, no
substates) works correctly; pcie_aspm.policy=powersupersave bricks the
card on every boot. The 6.x-era blanket `no_d3cold` quirk for Battlemage
was narrowed to ASUS NUC13 only in 7.0, but that change is orthogonal:
the failure here is link-state, not device-state, and surfaces
regardless of d3cold_allowed.

Disable all four L1SS substates (ASPM_L1.1, ASPM_L1.2, PCI-PM_L1.1,
PCI-PM_L1.2) on the BMG card's upstream port via a final PCI fixup.
Standard ASPM L1 still applies, so the link still benefits from the
deepest substate the BMG silicon actually handles correctly. The
quirk is keyed on the upstream-port device ID 0xe2ff so it covers
all current Battlemage SKUs (the GPU-endpoint ID varies by SKU, but
the upstream switch is shared).

Empirical narrowing (verified post-fix): with a partial mask that
disabled only ASPM_L1.{1,2} but left PCI-PM_L1.{1,2} armed, the
system boots and operates correctly. This isolates ASPM_L1.1 as the
specific trigger of the brick (the AMD root port advertises ASPM_L1.1
but not ASPM_L1.2, so ASPM_L1.2 cannot have been activated). The
PCI-PM substates only activate during D3hot transitions which the
GPU does not undergo during normal use; they are disabled here for
hygiene rather than necessity.

Reported-by: Pavel Shirshov <pavel@xxxxxxxx>
Signed-off-by: <FILL IN BEFORE SUBMITTING UPSTREAM>

--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -6289,6 +6289,34 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56b0, aspm_l1_acceptable_latency
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56b1, aspm_l1_acceptable_latency);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c0, aspm_l1_acceptable_latency);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c1, aspm_l1_acceptable_latency);
+
+/*
+ * Intel Battlemage discrete GPU cards (BMG-G21 / BMG-G31; Arc B580,
+ * Arc Pro B50/B60/B70) expose a two-layer on-card PCIe switch. The
+ * platform-facing link, between the host root port and the card's
+ * upstream switch port (PCI device ID 0xe2ff), is the only link in the
+ * chain advertising L1 PM Substates on both ends. On at least AMD
+ * Starship/Matisse root ports, where the intersection is ASPM_L1.1
+ * only, arming L1.1 leaves the BMG card unable to wake from D3cold:
+ *
+ * pcieport 0000:02:01.0: Unable to change power state from D3cold
+ * to D0, device inaccessible
+ * xe 0000:03:00.0: probe with driver xe failed with error -71
+ *
+ * Reproduces deterministically with pcie_aspm.policy=powersupersave,
+ * works correctly with policy=powersave (no substates). Disable L1SS
+ * substates on the BMG card upstream port; standard L1 ASPM is
+ * unaffected.
+ */
+static void quirk_intel_bmg_no_l1ss(struct pci_dev *dev)
+{
+ pci_disable_link_state(dev, PCIE_LINK_STATE_L1_2 |
+ PCIE_LINK_STATE_L1_1 |
+ PCIE_LINK_STATE_L1_2_PCIPM |
+ PCIE_LINK_STATE_L1_1_PCIPM);
+ pci_info(dev, "intel-bmg-aspm-quirk: L1.1/L1.2 substates disabled on BMG upstream port\n");
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0xe2ff, quirk_intel_bmg_no_l1ss);
#endif

#ifdef CONFIG_PCIE_DPC