[PATCH 5.15.y 1/2] usb: typec: tcpm: fix debug accessory mode detection for sink ports

[Sasha Levin <sashal@kernel.org>]

From: Xu Yang <xu.yang_2@nxp.com>

[ Upstream commit f6ec9bb4acc7182b25a793ad094a764e1cb819a7 ]

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. Also update the logic
in run_state_machine() to keep consistency.

Fixes: 8db73e6a42b6 ("usb: typec: tcpm: allow sink (ufp) to toggle into accessory mode debug")
Cc: stable <stable@kernel.org>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Amit Sunil Dhamne <amitsd@google.com>
Link: https://patch.msgid.link/20260424074009.2979266-1-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[Backport to 6.12: This tree lacks 8db73e6a42b6 and the associated
sink debug-accessory state-machine support. Retain only the source-debug
macro extraction and source-side call-site updates. Keep
tcpm_port_is_debug() source-only and omit the sink-debug macro and all
sink/audio attachment transitions introduced by the upstream dependency.
This preserves existing detection and state transitions while providing
tcpm_port_is_debug_source() for cd3b9cea675b ("usb: typec: tcpm: constrain
TCPM_SOURCING_VBUS event handling"). No functions are added.]

Stable-dep-of: cd3b9cea675b ("usb: typec: tcpm: constrain TCPM_SOURCING_VBUS event handling")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/typec/tcpm/tcpm.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index ce997d6844f3f..319392756c20c 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -514,9 +514,12 @@ static const char * const pd_rev[] = {
 	 (tcpm_cc_is_source((port)->cc2) && \
 	  !tcpm_cc_is_source((port)->cc1)))
 
-#define tcpm_port_is_debug(port) \
+#define tcpm_port_is_debug_source(port) \
 	(tcpm_cc_is_source((port)->cc1) && tcpm_cc_is_source((port)->cc2))
 
+#define tcpm_port_is_debug(port) \
+	tcpm_port_is_debug_source(port)
+
 #define tcpm_port_is_audio(port) \
 	(tcpm_cc_is_audio((port)->cc1) && tcpm_cc_is_audio((port)->cc2))
 
@@ -3951,7 +3954,7 @@ static void run_state_machine(struct tcpm_port *port)
 			tcpm_set_state(port, SNK_UNATTACHED, PD_T_DRP_SNK);
 		break;
 	case SRC_ATTACH_WAIT:
-		if (tcpm_port_is_debug(port))
+		if (tcpm_port_is_debug_source(port))
 			tcpm_set_state(port, DEBUG_ACC_ATTACHED,
 				       PD_T_CC_DEBOUNCE);
 		else if (tcpm_port_is_audio(port))
@@ -4954,7 +4957,7 @@ 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))
@@ -4962,7 +4965,7 @@ 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);
 		break;
-- 
2.53.0