linux-kernel - Re: [PATCH] usb: typec: tcpm: fix state transition for SNK_WAIT_CAPABILITIES state in run_state

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Message-ID: <Z9FyLNcHHczSvpAq@kuha.fi.intel.com>
Date: Wed, 12 Mar 2025 13:38:20 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: amitsd@...gle.com
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Badhri Jagan Sridharan <badhri@...gle.com>,
	RD Babiera <rdbabiera@...gle.com>, Kyle Tso <kyletso@...gle.com>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	Xu Yang <xu.yang_2@....com>, stable@...r.kernel.org
Subject: Re: [PATCH] usb: typec: tcpm: fix state transition for
 SNK_WAIT_CAPABILITIES state in run_state_machine()

On Mon, Mar 10, 2025 at 07:19:07PM -0700, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@...gle.com>
> 
> A subtle error got introduced while manually fixing merge conflict in
> tcpm.c for commit 85c4efbe6088 ("Merge v6.12-rc6 into usb-next"). As a
> result of this error, the next state is unconditionally set to
> SNK_WAIT_CAPABILITIES_TIMEOUT while handling SNK_WAIT_CAPABILITIES state
> in run_state_machine(...).
> 
> Fix this by setting new state of TCPM state machine to `upcoming_state`
> (that is set to different values based on conditions).
> 
> Cc: stable@...r.kernel.org
> Fixes: 85c4efbe60888 ("Merge v6.12-rc6 into usb-next")
> Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
> Reviewed-by: Badhri Jagan Sridharan <badhri@...gle.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 47be450d2be352698e9dee2e283664cd4db8081b..758933d4ac9e4e55d45940b068f3c416e7e51ee8 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -5117,16 +5117,16 @@ static void run_state_machine(struct tcpm_port *port)
>  		 */
>  		if (port->vbus_never_low) {
>  			port->vbus_never_low = false;
> -			tcpm_set_state(port, SNK_SOFT_RESET,
> -				       port->timings.sink_wait_cap_time);
> +			upcoming_state = SNK_SOFT_RESET;
>  		} else {
>  			if (!port->self_powered)
>  				upcoming_state = SNK_WAIT_CAPABILITIES_TIMEOUT;
>  			else
>  				upcoming_state = hard_reset_state(port);
> -			tcpm_set_state(port, SNK_WAIT_CAPABILITIES_TIMEOUT,
> -				       port->timings.sink_wait_cap_time);
>  		}
> +
> +		tcpm_set_state(port, upcoming_state,
> +			       port->timings.sink_wait_cap_time);
>  		break;
>  	case SNK_WAIT_CAPABILITIES_TIMEOUT:
>  		/*
> 
> ---
> base-commit: 5c8c229261f14159b54b9a32f12e5fa89d88b905
> change-id: 20250310-fix-snk-wait-timeout-v6-14-rc6-7b4d9fb9bc99
> 
> Best regards,
> -- 
> Amit Sunil Dhamne <amitsd@...gle.com>
> 

-- 
heikki