linux-kernel - [PATCH] usb: typec: tcpm: support sink port for debounce

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Date: Tue, 12 Mar 2024 09:13:00 +0800
From: Michael Wu <michael@...winnertech.com>
To: heikki.krogerus@...ux.intel.com,
	gregkh@...uxfoundation.org,
	linux@...ck-us.net,
	badhri@...gle.com,
	kyletso@...gle.com,
	frank.wang@...k-chips.com,
	rdbabiera@...gle.com,
	xu.yang_2@....com
Cc: linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] usb: typec: tcpm: support sink port for debounce

When both CC1 and CC2 pins are simultaneously pulled up, it often leads
to the double Rp to Vbus cable being stuck in the SNK_ATTACH_WAIT state.
And the state machine fails to transition to the SNK_ATTACHED state.

Therefore, it is recommended to focus on transitioning the sink port to
the SNK_DEBOUNCED state instead. By doing so, the desired outcome can be
achieved more effectively.

[  134.525750] VBUS on
[  134.713240] CC1: 0 -> 3, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
[  134.713249] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]

Signed-off-by: Michael Wu <michael@...winnertech.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 0965972310275..9228dbd78bf2b 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4197,6 +4197,8 @@ static void run_state_machine(struct tcpm_port *port)
 		else if (tcpm_port_is_disconnected(port))
 			tcpm_set_state(port, SNK_UNATTACHED,
 				       PD_T_PD_DEBOUNCE);
+		else if (tcpm_port_is_sink(port))
+			tcpm_set_state(port, SNK_DEBOUNCED, 0);
 		break;
 	case SNK_DEBOUNCED:
 		if (tcpm_port_is_disconnected(port))
-- 
2.29.0