linux-kernel - Re: [PATCH 06/11 v2] staging: typec: tcpm: Comply with TryWait.SNK State

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Date:   Sun, 27 Aug 2017 10:24:58 -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 06/11 v2] staging: typec: tcpm: Comply with TryWait.SNK
 State

On Sat, Aug 26, 2017 at 11:49:21PM -0700, Badhri Jagan Sridharan wrote:
> According to the spec:
> "4.5.2.2.10.2 Exiting from TryWait.SNK State
> The port shall transition to Attached.SNK after tCCDebounce if or when VBUS
> is detected. Note the Source may initiate USB PD communications which will
> cause brief periods of the SNK.Open state on both the CC1 and CC2 pins,
> but this event will not exceed tPDDebounce. The port shall transition to
> Unattached.SNK when the state of both of the CC1 and CC2 pins is SNK.Open
> for at least tPDDebounce."
> 
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>
> ---
> Changelog since v1:
> - Corrected  tag
> 
For v2 up to here:

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

>  drivers/staging/typec/tcpm.c | 58 +++++++++++++++++++++++---------------------
>  1 file changed, 30 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index fc179bdea7e4..0ae33330a5c7 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -2403,26 +2403,24 @@ static void run_state_machine(struct tcpm_port *port)
>  		break;
>  	case SNK_TRYWAIT:
>  		tcpm_set_cc(port, TYPEC_CC_RD);
> -		tcpm_set_state(port, SNK_TRYWAIT_DEBOUNCE, PD_T_CC_DEBOUNCE);
> +		tcpm_set_state(port, SNK_TRYWAIT_VBUS, PD_T_CC_DEBOUNCE);
>  		break;
> -	case SNK_TRYWAIT_DEBOUNCE:
> -		if (port->vbus_present) {
> +	case SNK_TRYWAIT_VBUS:
> +		/*
> +		 * TCPM stays in this state indefinitely until VBUS
> +		 * is detected as long as Rp is not detected for
> +		 * more than a time period of tPDDebounce.
> +		 */
> +		if (port->vbus_present && tcpm_port_is_sink(port)) {
>  			tcpm_set_state(port, SNK_ATTACHED, 0);
>  			break;
>  		}
> -		if (tcpm_port_is_disconnected(port)) {
> -			tcpm_set_state(port, SNK_UNATTACHED,
> -				       PD_T_PD_DEBOUNCE);
> -			break;
> -		}
> -		if (tcpm_port_is_source(port))
> -			tcpm_set_state(port, SRC_ATTACHED, 0);
> -		/* XXX Are we supposed to stay in this state ? */
> +		if (!tcpm_port_is_sink(port))
> +			tcpm_set_state(port, SNK_TRYWAIT_DEBOUNCE, 0);
>  		break;
> -	case SNK_TRYWAIT_VBUS:
> -		tcpm_set_state(port, SNK_ATTACHED, PD_T_CC_DEBOUNCE);
> +	case SNK_TRYWAIT_DEBOUNCE:
> +		tcpm_set_state(port, SNK_UNATTACHED, PD_T_PD_DEBOUNCE);
>  		break;
> -
>  	case SNK_ATTACHED:
>  		ret = tcpm_snk_attach(port);
>  		if (ret < 0)
> @@ -2960,19 +2958,16 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>  		tcpm_set_state(port, SRC_TRY_WAIT, 0);
>  		break;
>  	case SNK_TRYWAIT_DEBOUNCE:
> -		if (port->vbus_present) {
> -			tcpm_set_state(port, SNK_ATTACHED, 0);
> -			break;
> -		}
> -		if (tcpm_port_is_source(port)) {
> -			tcpm_set_state(port, SRC_ATTACHED, 0);
> -			break;
> -		}
> -		if (tcpm_port_is_disconnected(port) &&
> -		    port->delayed_state != SNK_UNATTACHED)
> +		if (tcpm_port_is_sink(port))
> +			tcpm_set_state(port, SNK_TRYWAIT_VBUS, 0);
> +		break;
> +	case SNK_TRYWAIT_VBUS:
> +		if (!tcpm_port_is_sink(port))
>  			tcpm_set_state(port, SNK_TRYWAIT_DEBOUNCE, 0);
>  		break;
> -
> +	case SNK_TRYWAIT:
> +		/* Do nothing, waiting for tCCDebounce */
> +		break;
>  	case PR_SWAP_SNK_SRC_SINK_OFF:
>  	case PR_SWAP_SRC_SNK_TRANSITION_OFF:
>  	case PR_SWAP_SRC_SNK_SOURCE_OFF:
> @@ -3030,7 +3025,14 @@ static void _tcpm_pd_vbus_on(struct tcpm_port *port)
>  		/* Do nothing, waiting for PD_DEBOUNCE to do be done */
>  		break;
>  	case SNK_TRYWAIT:
> -		tcpm_set_state(port, SNK_TRYWAIT_VBUS, 0);
> +		/* Do nothing, waiting for tCCDebounce */
> +		break;
> +	case SNK_TRYWAIT_VBUS:
> +		if (tcpm_port_is_sink(port))
> +			tcpm_set_state(port, SNK_ATTACHED, 0);
> +		break;
> +	case SNK_TRYWAIT_DEBOUNCE:
> +		/* Do nothing, waiting for Rp */
>  		break;
>  	case SRC_TRY_WAIT:
>  	case SRC_TRY_DEBOUNCE:
> @@ -3067,10 +3069,10 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>  	case SNK_TRY_WAIT_DEBOUNCE:
>  		/* Do nothing, waiting for PD_DEBOUNCE to do be done */
>  		break;
> +	case SNK_TRYWAIT:
>  	case SNK_TRYWAIT_VBUS:
> -		tcpm_set_state(port, SNK_TRYWAIT, 0);
> +	case SNK_TRYWAIT_DEBOUNCE:
>  		break;
> -
>  	case SNK_ATTACH_WAIT:
>  		tcpm_set_state(port, SNK_UNATTACHED, 0);
>  		break;
> -- 
> 2.14.1.342.g6490525c54-goog
>