linux-kernel - [PATCH v2] usb: typec: tpcm: Fix PORT_RESET behavior for self powered devices

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Message-ID: <20240228000512.746252-1-badhri@google.com>
Date: Wed, 28 Feb 2024 00:05:12 +0000
From: Badhri Jagan Sridharan <badhri@...gle.com>
To: gregkh@...uxfoundation.org, linux@...ck-us.net, 
	heikki.krogerus@...ux.intel.com
Cc: kyletso@...gle.com, linux-usb@...r.kernel.org, 
	linux-kernel@...r.kernel.org, rdbabiera@...gle.com, amitsd@...gle.com, 
	stable@...r.kernel.org, frank.wang@...k-chips.com, broonie@...nel.org, 
	Badhri Jagan Sridharan <badhri@...gle.com>
Subject: [PATCH v2] usb: typec: tpcm: Fix PORT_RESET behavior for self powered devices

While commit 69f89168b310 ("usb: typec: tpcm: Fix issues with power being
removed during reset") fixes the boot issues for bus powered devices such
as LibreTech Renegade Elite/Firefly, it trades off the CC pins NOT being
Hi-Zed during errory recovery (i.e PORT_RESET) for devices which are NOT
bus powered(a.k.a self powered). This change Hi-Zs the CC pins only for
self powered devices, thus preventing brown out for bus powered devices

Adhering to spec is gaining more importance due to the Common charger
initiative enforced by the European Union.

Quoting from the spec:
    4.5.2.2.2.1 ErrorRecovery State Requirements
    The port shall not drive VBUS or VCONN, and shall present a
    high-impedance to ground (above zOPEN) on its CC1 and CC2 pins.

Hi-Zing the CC pins is the inteded behavior for PORT_RESET.
CC pins are set to default state after tErrorRecovery in
PORT_RESET_WAIT_OFF.

    4.5.2.2.2.2 Exiting From ErrorRecovery State
    A Sink shall transition to Unattached.SNK after tErrorRecovery.
    A Source shall transition to Unattached.SRC after tErrorRecovery.

Fixes: 69f89168b310 ("usb: typec: tpcm: Fix issues with power being removed during reset")
Cc: stable@...r.kernel.org
Cc: Mark Brown <broonie@...nel.org>
Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
Changes since V1:
* Fix CC for linux stable
---
 drivers/usb/typec/tcpm/tcpm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index c9a78f55ca48..bbe1381232eb 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -5593,8 +5593,11 @@ static void run_state_machine(struct tcpm_port *port)
 		break;
 	case PORT_RESET:
 		tcpm_reset_port(port);
-		tcpm_set_cc(port, tcpm_default_state(port) == SNK_UNATTACHED ?
-			    TYPEC_CC_RD : tcpm_rp_cc(port));
+		if (port->self_powered)
+			tcpm_set_cc(port, TYPEC_CC_OPEN);
+		else
+			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: a560a5672826fc1e057068bda93b3d4c98d037a2
-- 
2.44.0.rc1.240.g4c46232300-goog