usb_pd: TCPMv1: Enable VCONN swap at explicit contract

According to Section 2.6.2 of both USB-PD Spec Revision 2.0, Version 1.3
& USB-PD Spec Revision 3.0, Version 2.0, at explicit contract, The Sink
can initiate or receive a request for an exchange of VCONN Source and
The Sink when it is the VCONN Source can communicate with a Cable Plug
using SOP’ or SOP’’ Communication.

PD_FLAGS_CHECK_VCONN_STATE flag enables the DUT to request for a VCONN
swap at explicit contract.

Earlier, when UFP requested for a power role swap,
PD_FLAGS_CHECK_VCONN_STATE flag wasn't being enabled and hence, DUT was
not entering Thunderbolt/USB4 alternate mode.

Enabling the PD_FLAGS_CHECK_VCONN_STATE flag in PD_STATE_SNK_REQUESTED
and in PD_STATE_SRC_POWERED allows DUT to request for VCONN swap at
explicit contract.

BUG=b:158455025
BRANCH=None
TEST=Able to enter into Thunderbolt/USB4 when UFP requests for a power
     role swap.

Change-Id: I68f2e2de3186ea367ace497b47930e30976c9e6b
Signed-off-by: Ayushee <ayushee.shah@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2244022
Tested-by: Keith Short <keithshort@chromium.org>
Reviewed-by: Keith Short <keithshort@chromium.org>
Commit-Queue: Keith Short <keithshort@chromium.org>

1 files changed, 19 insertions, 18 deletions

diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index b8cd5d7340..99d1e33ae1 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -3608,6 +3608,7 @@ void pd_task(void *u)
 		case PD_STATE_SRC_POWERED:
 			/* Switch to the new requested voltage */
 			if (pd[port].last_state != pd[port].task_state) {
+				pd[port].flags |= PD_FLAGS_CHECK_VCONN_STATE;
 				pd_transition_voltage(pd[port].requested_idx);
 				set_state_timeout(
 					port,
@@ -3696,18 +3697,9 @@ void pd_task(void *u)
 				pd_check_pr_role(port, PD_ROLE_SOURCE,
 						 pd[port].flags);
 				pd[port].flags &= ~PD_FLAGS_CHECK_PR_ROLE;
-				/*
-				 * USB PD  version 1.3 section 2.6.1:
-				 * During Explicit contract the Sink can
-				 * initiate or receive a request an exchange
-				 * of VCONN Source. Hence, enable Vconn swap
-				 * during explicit contract.
-				 */
-				pd[port].flags |= PD_FLAGS_CHECK_VCONN_STATE;
-
-				break;
 			}
 
+
 			/* Check data role policy, which may trigger a swap */
 			if (pd[port].flags & PD_FLAGS_CHECK_DR_ROLE) {
 				pd_check_dr_role(port, pd[port].data_role,
@@ -3718,6 +3710,14 @@ void pd_task(void *u)
 
 			/* Check for Vconn source, which may trigger a swap */
 			if (pd[port].flags & PD_FLAGS_CHECK_VCONN_STATE) {
+				/*
+				 * Ref: Section 2.6.1 of both
+				 * USB-PD Spec Revision 2.0, Version 1.3 &
+				 * USB-PD Spec Revision 3.0, Version 2.0
+				 * During Explicit contract the Sink can
+				 * initiate or receive a request an exchange
+				 * of VCONN Source.
+				 */
 				pd_try_execute_vconn_swap(port,
 							  pd[port].flags);
 				pd[port].flags &= ~PD_FLAGS_CHECK_VCONN_STATE;
@@ -4268,6 +4268,7 @@ void pd_task(void *u)
 		case PD_STATE_SNK_REQUESTED:
 			/* Wait for ACCEPT or REJECT */
 			if (pd[port].last_state != pd[port].task_state) {
+				pd[port].flags |= PD_FLAGS_CHECK_VCONN_STATE;
 				hard_reset_count = 0;
 				set_state_timeout(port,
 						  get_time().val +
@@ -4318,14 +4319,6 @@ void pd_task(void *u)
 				pd_check_pr_role(port, PD_ROLE_SINK,
 						 pd[port].flags);
 				pd[port].flags &= ~PD_FLAGS_CHECK_PR_ROLE;
-				/*
-				 * USB PD  version 1.3 section 2.6.2:
-				 * During Explicit contract the Sink can
-				 * initiate or receive a request an exchange
-				 * of VCONN Source. Hence, enable Vconn swap
-				 * during explicit contract.
-				 */
-				pd[port].flags |= PD_FLAGS_CHECK_VCONN_STATE;
 				break;
 			}
 
@@ -4339,6 +4332,14 @@ void pd_task(void *u)
 
 			/* Check for Vconn source, which may trigger a swap */
 			if (pd[port].flags & PD_FLAGS_CHECK_VCONN_STATE) {
+				/*
+				 * Ref: Section 2.6.2 of both
+				 * USB-PD Spec Revision 2.0, Version 1.3 &
+				 * USB-PD Spec Revision 3.0, Version 2.0
+				 * During Explicit contract the Sink can
+				 * initiate or receive a request an exchange
+				 * of VCONN Source.
+				 */
 				pd_try_execute_vconn_swap(port,
 							  pd[port].flags);
 				pd[port].flags &= ~PD_FLAGS_CHECK_VCONN_STATE;