[PATCH] usb: typec: tcpm: fix debug accessory mode detection for sink ports

[PATCH] usb: typec: tcpm: fix debug accessory mode detection for sink ports

[Xu Yang]

The port in debug accessory mode can be either a source or sink. The
previous tcpm_port_is_debug() function only checked for source port.

Commit 8db73e6a42b6 ("usb: typec: tcpm: allow sink (ufp) to toggle into
accessory mode debug") changed the detection logic to support both roles,
but left some logic in _tcpm_cc_change() unchanged, This causes the state
machine to transition to an incorrect state when operating as a sink in
debug accessory mode. Log as below:

[  978.637541] CC1: 0 -> 5, CC2: 0 -> 5 [state TOGGLING, polarity 0, connected]
[  978.637567] state change TOGGLING -> SRC_ATTACH_WAIT [rev1 NONE_AMS]
[  978.637596] pending state change SRC_ATTACH_WAIT -> DEBUG_ACC_ATTACHED @ 180 ms [rev1 NONE_AMS]
[  978.647098] CC1: 5 -> 0, CC2: 5 -> 5 [state SRC_ATTACH_WAIT, polarity 0, connected]
[  978.647115] state change SRC_ATTACH_WAIT -> SRC_ATTACH_WAIT [rev1 NONE_AMS]

It should go to SNK_ATTACH_WAIT instead of SRC_ATTACH_WAIT state.

To fix this, add tcpm_port_is_debug_source() and tcpm_port_is_debug_sink()
helper to explicitly identify the power mode in debug accessory mode.
Update the state transition logic in _tcpm_cc_change() to ensure the state
machine transitions comply with Type-C specification.

Fixes: 8db73e6a42b6 ("usb: typec: tcpm: allow sink (ufp) to toggle into accessory mode debug")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index dfbb94ddc98a..1ee00025de56 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -732,9 +732,14 @@ static const char * const pd_rev[] = {
 	 (tcpm_cc_is_source((port)->cc2) && \
 	  !tcpm_cc_is_source((port)->cc1)))
 
+#define tcpm_port_is_debug_source(port) \
+	(tcpm_cc_is_source((port)->cc1) && tcpm_cc_is_source((port)->cc2))
+
+#define tcpm_port_is_debug_sink(port) \
+	(tcpm_cc_is_sink((port)->cc1) && tcpm_cc_is_sink((port)->cc2))
+
 #define tcpm_port_is_debug(port) \
-	((tcpm_cc_is_source((port)->cc1) && tcpm_cc_is_source((port)->cc2)) || \
-	 (tcpm_cc_is_sink((port)->cc1) && tcpm_cc_is_sink((port)->cc2)))
+	(tcpm_port_is_debug_source(port) || tcpm_port_is_debug_sink(port))
 
 #define tcpm_port_is_audio(port) \
 	(tcpm_cc_is_audio((port)->cc1) && tcpm_cc_is_audio((port)->cc2))
@@ -6360,10 +6365,10 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 
 	switch (port->state) {
 	case TOGGLING:
-		if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
+		if (tcpm_port_is_debug_source(port) || tcpm_port_is_audio(port) ||
 		    tcpm_port_is_source(port))
 			tcpm_set_state(port, SRC_ATTACH_WAIT, 0);
-		else if (tcpm_port_is_sink(port))
+		else if (tcpm_port_is_debug_sink(port) || tcpm_port_is_sink(port))
 			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
 		break;
 	case CHECK_CONTAMINANT:
@@ -6371,9 +6376,11 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		break;
 	case SRC_UNATTACHED:
 	case ACC_UNATTACHED:
-		if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
+		if (tcpm_port_is_debug_source(port) || tcpm_port_is_audio(port) ||
 		    tcpm_port_is_source(port))
 			tcpm_set_state(port, SRC_ATTACH_WAIT, 0);
+		else if (tcpm_port_is_debug_sink(port))
+			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
 		break;
 	case SRC_ATTACH_WAIT:
 		if (tcpm_port_is_disconnected(port) ||
@@ -6395,7 +6402,7 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		}
 		break;
 	case SNK_UNATTACHED:
-		if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
+		if (tcpm_port_is_debug_sink(port) || tcpm_port_is_audio(port) ||
 		    tcpm_port_is_sink(port))
 			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
 		break;
-- 
2.34.1