linux-kernel - Re: [PATCH 5/6] staging: usb: tcpm: usb: typec: tcpm: Follow Try.SRC exit requirements

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Date:   Sun, 27 Aug 2017 10:22:29 -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 5/6] staging: usb: tcpm: usb: typec: tcpm: Follow Try.SRC
 exit requirements

On Sat, Aug 26, 2017 at 10:25:07PM -0700, Badhri Jagan Sridharan wrote:
> According to spec:
> " 4.5.2.2.9.2 Exiting from Try.SRC State:
> The port shall transition to Attached.SRC when the SRC.Rd
> state is detected on exactly one of the CC1 or CC2 pins for
> at least tPDDebounce. The port shall transition to
> TryWait.SNK after tDRPTry and the SRC.Rd state has not been
> detected."
> 
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>

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

> ---
>  drivers/staging/typec/tcpm.c | 33 ++++++++++++++++++++++++++++-----
>  1 file changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index 7eed04698ebe..fc179bdea7e4 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -112,6 +112,7 @@
>  	S(SRC_TRYWAIT_UNATTACHED),		\
>  						\
>  	S(SRC_TRY),				\
> +	S(SRC_TRY_WAIT),                        \
>  	S(SRC_TRY_DEBOUNCE),			\
>  	S(SNK_TRYWAIT),				\
>  	S(SNK_TRYWAIT_DEBOUNCE),		\
> @@ -2158,6 +2159,7 @@ static void run_state_machine(struct tcpm_port *port)
>  {
>  	int ret;
>  	enum typec_pwr_opmode opmode;
> +	unsigned int msecs;
>  
>  	port->enter_state = port->state;
>  	switch (port->state) {
> @@ -2379,7 +2381,22 @@ static void run_state_machine(struct tcpm_port *port)
>  	case SRC_TRY:
>  		port->try_src_count++;
>  		tcpm_set_cc(port, tcpm_rp_cc(port));
> -		tcpm_set_state(port, SNK_TRYWAIT, PD_T_DRP_TRY);
> +		port->max_wait = 0;
> +		tcpm_set_state(port, SRC_TRY_WAIT, 0);
> +		break;
> +	case SRC_TRY_WAIT:
> +		if (port->max_wait == 0) {
> +			port->max_wait = jiffies +
> +					 msecs_to_jiffies(PD_T_DRP_TRY);
> +			msecs = PD_T_DRP_TRY;
> +		} else {
> +			if (time_is_after_jiffies(port->max_wait))
> +				msecs = jiffies_to_msecs(port->max_wait -
> +							 jiffies);
> +			else
> +				msecs = 0;
> +		}
> +		tcpm_set_state(port, SNK_TRYWAIT, msecs);
>  		break;
>  	case SRC_TRY_DEBOUNCE:
>  		tcpm_set_state(port, SRC_ATTACHED, PD_T_PD_DEBOUNCE);
> @@ -2935,12 +2952,12 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>  			tcpm_set_state(port, SRC_TRYWAIT, 0);
>  		}
>  		break;
> -	case SRC_TRY:
> +	case SRC_TRY_WAIT:
>  		if (tcpm_port_is_source(port))
>  			tcpm_set_state(port, SRC_TRY_DEBOUNCE, 0);
>  		break;
>  	case SRC_TRY_DEBOUNCE:
> -		tcpm_set_state(port, SRC_TRY, 0);
> +		tcpm_set_state(port, SRC_TRY_WAIT, 0);
>  		break;
>  	case SNK_TRYWAIT_DEBOUNCE:
>  		if (port->vbus_present) {
> @@ -3015,7 +3032,10 @@ static void _tcpm_pd_vbus_on(struct tcpm_port *port)
>  	case SNK_TRYWAIT:
>  		tcpm_set_state(port, SNK_TRYWAIT_VBUS, 0);
>  		break;
> -
> +	case SRC_TRY_WAIT:
> +	case SRC_TRY_DEBOUNCE:
> +		/* Do nothing, waiting for sink detection */
> +		break;
>  	default:
>  		break;
>  	}
> @@ -3069,7 +3089,10 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>  	case PORT_RESET_WAIT_OFF:
>  		tcpm_set_state(port, tcpm_default_state(port), 0);
>  		break;
> -
> +	case SRC_TRY_WAIT:
> +	case SRC_TRY_DEBOUNCE:
> +		/* Do nothing, waiting for sink detection */
> +		break;
>  	default:
>  		if (port->pwr_role == TYPEC_SINK &&
>  		    port->attached)
> -- 
> 2.14.1.342.g6490525c54-goog
>