linux-kernel - Re: [PATCH 08/11] staging: typec: tcpm: add cc change handling in src states

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Message-ID: <20170827172546.GR22819@roeck-us.net>
Date:   Sun, 27 Aug 2017 10:25:46 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Badhri Jagan Sridharan <badhri@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/11] staging: typec: tcpm: add cc change handling in
 src states

On Sat, Aug 26, 2017 at 11:50:31PM -0700, Badhri Jagan Sridharan wrote:
> In the case that the lower layer driver reports a cc change directly
> from SINK state to SOURCE state, TCPM doesn't handle these cc change
> in SRC_SEND_CAPABILITIES, SRC_READY states. And with SRC_ATTACHED
> state, the change is not handled as the port is still considered
> connected.
> 
> [49606.131672] state change DRP_TOGGLING -> SRC_ATTACH_WAIT
> [49606.131701] pending state change SRC_ATTACH_WAIT -> SRC_ATTACHED @
> 200 ms
> [49606.329952] state change SRC_ATTACH_WAIT -> SRC_ATTACHED [delayed 200
> ms]
> [49606.329978] polarity 0
> [49606.329989] Requesting mux mode 1, config 0, polarity 0
> [49606.349416] vbus:=1 charge=0
> [49606.372274] pending state change SRC_ATTACHED -> SRC_UNATTACHED @ 480
> ms
> [49606.372431] VBUS on
> [49606.372488] state change SRC_ATTACHED -> SRC_STARTUP
> ...
> (the lower layer driver reports a direct change from source to sink)
> [49606.536927] pending state change SRC_SEND_CAPABILITIES ->
> SRC_SEND_CAPABILITIES @ 150 ms
> [49606.547244] CC1: 2 -> 5, CC2: 0 -> 0 [state SRC_SEND_CAPABILITIES,
> polarity 0, connected]
> 
> This can happen when the lower layer driver and/or the hardware
> handles a portion of the Type-C state machine work, and quietly goes
> through the unattached state.
> 
> Originally-from: Yueyao Zhu <yueyao@...gle.com>
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/staging/typec/tcpm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index 645f43ee83df..1f6827f32b29 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -2874,10 +2874,12 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>  			tcpm_set_state(port, SRC_ATTACH_WAIT, 0);
>  		break;
>  	case SRC_ATTACHED:
> -		if (tcpm_port_is_disconnected(port))
> +	case SRC_SEND_CAPABILITIES:
> +	case SRC_READY:
> +		if (tcpm_port_is_disconnected(port) ||
> +		    !tcpm_port_is_source(port))
>  			tcpm_set_state(port, SRC_UNATTACHED, 0);
>  		break;
> -
>  	case SNK_UNATTACHED:
>  		if (tcpm_port_is_sink(port))
>  			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
> -- 
> 2.14.1.342.g6490525c54-goog
>