[PATCH 5.12 126/173] usb: typec: tcpm: Correct the responses in SVDM Version 2.0 DFP

[Greg Kroah-Hartman]

From: Kyle Tso <kyletso@xxxxxxxxxx>

commit f41bfc7e9c7c1d721c8752f1853cde43e606ad43 upstream.

In USB PD Spec Rev 3.1 Ver 1.0, section "6.12.5 Applicability of
Structured VDM Commands", DFP is allowed and recommended to respond to
Discovery Identity with ACK. And in section "6.4.4.2.5.1 Commands other
than Attention", NAK should be returned only when receiving Messages
with invalid fields, Messages in wrong situation, or unrecognize
Messages.

Still keep the original design for SVDM Version 1.0 for backward
compatibilities.

Fixes: 193a68011fdc ("staging: typec: tcpm: Respond to Discover Identity commands")
Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Signed-off-by: Kyle Tso <kyletso@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210601123151.3441914-2-kyletso@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/typec/tcpm/tcpm.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1531,19 +1531,25 @@ static int tcpm_pd_svdm(struct tcpm_port
 			if (PD_VDO_VID(p[0]) != USB_SID_PD)
 				break;
 
-			if (PD_VDO_SVDM_VER(p[0]) < svdm_version)
+			if (PD_VDO_SVDM_VER(p[0]) < svdm_version) {
 				typec_partner_set_svdm_version(port->partner,
 							       PD_VDO_SVDM_VER(p[0]));
+				svdm_version = PD_VDO_SVDM_VER(p[0]);
+			}
 
 			tcpm_ams_start(port, DISCOVER_IDENTITY);
-			/* 6.4.4.3.1: Only respond as UFP (device) */
-			if (port->data_role == TYPEC_DEVICE &&
+			/*
+			 * PD2.0 Spec 6.10.3: respond with NAK as DFP (data host)
+			 * PD3.1 Spec 6.4.4.2.5.1: respond with NAK if "invalid field" or
+			 * "wrong configuation" or "Unrecognized"
+			 */
+			if ((port->data_role == TYPEC_DEVICE || svdm_version >= SVDM_VER_2_0) &&
 			    port->nr_snk_vdo) {
 				/*
 				 * Product Type DFP and Connector Type are not defined in SVDM
 				 * version 1.0 and shall be set to zero.
 				 */
-				if (typec_get_negotiated_svdm_version(typec) < SVDM_VER_2_0)
+				if (svdm_version < SVDM_VER_2_0)
 					response[1] = port->snk_vdo[0] & ~IDH_DFP_MASK
 						      & ~IDH_CONN_MASK;
 				else