Re: [PATCH v2] usb: typec: tcpm: Add additional checks for contaminant

[Heikki Krogerus]

On Sun, Oct 15, 2023 at 05:31:08AM +0000, Badhri Jagan Sridharan wrote:
> When transitioning from SNK_DEBOUNCED to unattached, its worthwhile to
> check for contaminant to mitigate wakeups.
> 
> ```
> [81334.219571] Start toggling
> [81334.228220] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> [81334.305147] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
> [81334.305162] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> [81334.305187] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> [81334.475515] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed 170 ms]
> [81334.486480] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_DEBOUNCED, polarity 0, disconnected]
> [81334.486495] state change SNK_DEBOUNCED -> SNK_DEBOUNCED [rev3 NONE_AMS]
> [81334.486515] pending state change SNK_DEBOUNCED -> SNK_UNATTACHED @ 20 ms [rev3 NONE_AMS]
> [81334.506621] state change SNK_DEBOUNCED -> SNK_UNATTACHED [delayed 20 ms]
> [81334.506640] Start toggling
> [81334.516972] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> [81334.592759] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
> [81334.592773] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> [81334.592792] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> [81334.762940] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed 170 ms]
> [81334.773557] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_DEBOUNCED, polarity 0, disconnected]
> [81334.773570] state change SNK_DEBOUNCED -> SNK_DEBOUNCED [rev3 NONE_AMS]
> [81334.773588] pending state change SNK_DEBOUNCED -> SNK_UNATTACHED @ 20 ms [rev3 NONE_AMS]
> [81334.793672] state change SNK_DEBOUNCED -> SNK_UNATTACHED [delayed 20 ms]
> [81334.793681] Start toggling
> [81334.801840] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> [81334.878655] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
> [81334.878672] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> [81334.878696] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> [81335.048968] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed 170 ms]
> [81335.060684] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_DEBOUNCED, polarity 0, disconnected]
> [81335.060754] state change SNK_DEBOUNCED -> SNK_DEBOUNCED [rev3 NONE_AMS]
> [81335.060775] pending state change SNK_DEBOUNCED -> SNK_UNATTACHED @ 20 ms [rev3 NONE_AMS]
> [81335.080884] state change SNK_DEBOUNCED -> SNK_UNATTACHED [delayed 20 ms]
> [81335.080900] Start toggling
> ```
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 599f008c257d ("usb: typec: tcpm: Add callbacks to mitigate wakeups due to contaminant")
> Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>

Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  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 6e843c511b85..1c7e8dc5282d 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -3903,6 +3903,8 @@ static void run_state_machine(struct tcpm_port *port)
>  		port->potential_contaminant = ((port->enter_state == SRC_ATTACH_WAIT &&
>  						port->state == SRC_UNATTACHED) ||
>  					       (port->enter_state == SNK_ATTACH_WAIT &&
> +						port->state == SNK_UNATTACHED) ||
> +					       (port->enter_state == SNK_DEBOUNCED &&
>  						port->state == SNK_UNATTACHED));
>  
>  	port->enter_state = port->state;
> 
> base-commit: 1034cc423f1b4a7a9a56d310ca980fcd2753e11d
> -- 
> 2.42.0.655.g421f12c284-goog

-- 
heikki