linux-kernel - [PATCH] usb: typec: tpcm: Fix issues with power being removed during reset

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Message-Id: <20240212-usb-fix-renegade-v1-1-22c43c88d635@kernel.org>
Date: Mon, 12 Feb 2024 18:42:13 +0000
From: Mark Brown <broonie@...nel.org>
To: Guenter Roeck <linux@...ck-us.net>, 
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Badhri Jagan Sridharan <badhri@...gle.com>, 
 Gábor Stefanik <netrolller.3d@...il.com>
Cc: rdbabiera@...gle.com, amitsd@...gle.com, linux-usb@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH] usb: typec: tpcm: Fix issues with power being removed
 during reset

Since the merge of b717dfbf73e8 ("Revert "usb: typec: tcpm: fix
cc role at port reset"") into mainline the LibreTech Renegade
Elite/Firefly has died during boot, the main symptom observed in testing
is a sudden stop in console output.  Gábor Stefanik identified in review
that the patch would cause power to be removed from devices without
batteries (like this board), observing that while the patch is correct
according to the spec this appears to be an oversight in the spec.

Given that the change makes previously working systems unusable let's
revert it, there was some discussion of identifying systems that have
alternative power and implementing the standards conforming behaviour in
only that case.

Fixes: b717dfbf73e8 ("Revert "usb: typec: tcpm: fix cc role at port reset"")
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/usb/typec/tcpm/tcpm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index f7d7daa60c8d..a0978ed1a257 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4876,7 +4876,8 @@ static void run_state_machine(struct tcpm_port *port)
 		break;
 	case PORT_RESET:
 		tcpm_reset_port(port);
-		tcpm_set_cc(port, TYPEC_CC_OPEN);
+		tcpm_set_cc(port, tcpm_default_state(port) == SNK_UNATTACHED ?
+			    TYPEC_CC_RD : tcpm_rp_cc(port));
 		tcpm_set_state(port, PORT_RESET_WAIT_OFF,
 			       PD_T_ERROR_RECOVERY);
 		break;

---
base-commit: 841c35169323cd833294798e58b9bf63fa4fa1de
change-id: 20240212-usb-fix-renegade-837d35cfc0c2

Best regards,
-- 
Mark Brown <broonie@...nel.org>