linux-kernel - Re: [PATCH 4/6] staging: usb: tcpm: usb: type-c: tcpm: Check for Rp for tPDDebounce

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Message-ID: <20170827172156.GN22819@roeck-us.net>
Date:   Sun, 27 Aug 2017 10:21:56 -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 4/6] staging: usb: tcpm: usb: type-c: tcpm: Check for Rp
 for tPDDebounce

On Sat, Aug 26, 2017 at 10:24:49PM -0700, Badhri Jagan Sridharan wrote:
> According the spec, the following is the conditions for exiting Try.SNK
> state:
> "The port shall wait for tDRPTry and only then begin monitoring the CC1 and
> CC2 pins for the SNK.Rp state. The port shall then transition to
> Attached.SNK when the SNK.Rp state is detected on exactly one of the CC1
> or CC2 pins for at least tPDDebounce and V BUS is detected. Alternatively,
> the port shall transition to TryWait.SRC if SNK.Rp state is not detected
> for tPDDebounce."
> 
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>

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

> ---
>  drivers/staging/typec/tcpm.c | 68 ++++++++++++++++----------------------------
>  1 file changed, 24 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index d45ffa8f2cfd..7eed04698ebe 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -105,6 +105,8 @@
>  						\
>  	S(SNK_TRY),				\
>  	S(SNK_TRY_WAIT),			\
> +	S(SNK_TRY_WAIT_DEBOUNCE),               \
> +	S(SNK_TRY_WAIT_DEBOUNCE_CHECK_VBUS),    \
>  	S(SRC_TRYWAIT),				\
>  	S(SRC_TRYWAIT_DEBOUNCE),		\
>  	S(SRC_TRYWAIT_UNATTACHED),		\
> @@ -2202,18 +2204,24 @@ static void run_state_machine(struct tcpm_port *port)
>  		tcpm_set_state(port, SNK_TRY_WAIT, PD_T_DRP_TRY);
>  		break;
>  	case SNK_TRY_WAIT:
> +		if (tcpm_port_is_sink(port)) {
> +			tcpm_set_state(port, SNK_TRY_WAIT_DEBOUNCE, 0);
> +		} else {
> +			tcpm_set_state(port, SRC_TRYWAIT, 0);
> +			port->max_wait = 0;
> +		}
> +		break;
> +	case SNK_TRY_WAIT_DEBOUNCE:
> +		tcpm_set_state(port, SNK_TRY_WAIT_DEBOUNCE_CHECK_VBUS,
> +			       PD_T_PD_DEBOUNCE);
> +		break;
> +	case SNK_TRY_WAIT_DEBOUNCE_CHECK_VBUS:
>  		if (port->vbus_present && tcpm_port_is_sink(port)) {
>  			tcpm_set_state(port, SNK_ATTACHED, 0);
> -			break;
> -		}
> -		if (!tcpm_port_is_sink(port)) {
> -			tcpm_set_state(port, SRC_TRYWAIT,
> -				       PD_T_PD_DEBOUNCE);
> +		} else {
> +			tcpm_set_state(port, SRC_TRYWAIT, 0);
>  			port->max_wait = 0;
> -			break;
>  		}
> -		/* No vbus, cc state is sink or open */
> -		tcpm_set_state(port, SRC_TRYWAIT_UNATTACHED, PD_T_DRP_TRYWAIT);
>  		break;
>  	case SRC_TRYWAIT:
>  		tcpm_set_cc(port, tcpm_rp_cc(port));
> @@ -2921,20 +2929,12 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>  		if (port->vbus_present || !tcpm_port_is_source(port))
>  			tcpm_set_state(port, SRC_TRYWAIT, 0);
>  		break;
> -	case SNK_TRY_WAIT:
> -		if (port->vbus_present && tcpm_port_is_sink(port)) {
> -			tcpm_set_state(port, SNK_ATTACHED, 0);
> -			break;
> +	case SNK_TRY_WAIT_DEBOUNCE:
> +		if (!tcpm_port_is_sink(port)) {
> +			port->max_wait = 0;
> +			tcpm_set_state(port, SRC_TRYWAIT, 0);
>  		}
> -		if (!tcpm_port_is_sink(port))
> -			new_state = SRC_TRYWAIT;
> -		else
> -			new_state = SRC_TRYWAIT_UNATTACHED;
> -
> -		if (new_state != port->delayed_state)
> -			tcpm_set_state(port, SNK_TRY_WAIT, 0);
>  		break;
> -
>  	case SRC_TRY:
>  		if (tcpm_port_is_source(port))
>  			tcpm_set_state(port, SRC_TRY_DEBOUNCE, 0);
> @@ -2974,8 +2974,6 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>  
>  static void _tcpm_pd_vbus_on(struct tcpm_port *port)
>  {
> -	enum tcpm_state new_state;
> -
>  	tcpm_log_force(port, "VBUS on");
>  	port->vbus_present = true;
>  	switch (port->state) {
> @@ -3011,18 +3009,8 @@ static void _tcpm_pd_vbus_on(struct tcpm_port *port)
>  	case SRC_TRYWAIT_DEBOUNCE:
>  		tcpm_set_state(port, SRC_TRYWAIT, 0);
>  		break;
> -	case SNK_TRY_WAIT:
> -		if (tcpm_port_is_sink(port)) {
> -			tcpm_set_state(port, SNK_ATTACHED, 0);
> -			break;
> -		}
> -		if (!tcpm_port_is_sink(port))
> -			new_state = SRC_TRYWAIT;
> -		else
> -			new_state = SRC_TRYWAIT_UNATTACHED;
> -
> -		if (new_state != port->delayed_state)
> -			tcpm_set_state(port, SNK_TRY_WAIT, 0);
> +	case SNK_TRY_WAIT_DEBOUNCE:
> +		/* Do nothing, waiting for PD_DEBOUNCE to do be done */
>  		break;
>  	case SNK_TRYWAIT:
>  		tcpm_set_state(port, SNK_TRYWAIT_VBUS, 0);
> @@ -3035,8 +3023,6 @@ static void _tcpm_pd_vbus_on(struct tcpm_port *port)
>  
>  static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>  {
> -	enum tcpm_state new_state;
> -
>  	tcpm_log_force(port, "VBUS off");
>  	port->vbus_present = false;
>  	port->vbus_never_low = false;
> @@ -3058,14 +3044,8 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>  		if (tcpm_port_is_source(port))
>  			tcpm_set_state(port, SRC_TRYWAIT_DEBOUNCE, 0);
>  		break;
> -	case SNK_TRY_WAIT:
> -		if (!tcpm_port_is_sink(port))
> -			new_state = SRC_TRYWAIT;
> -		else
> -			new_state = SRC_TRYWAIT_UNATTACHED;
> -
> -		if (new_state != port->delayed_state)
> -			tcpm_set_state(port, SNK_TRY_WAIT, 0);
> +	case SNK_TRY_WAIT_DEBOUNCE:
> +		/* Do nothing, waiting for PD_DEBOUNCE to do be done */
>  		break;
>  	case SNK_TRYWAIT_VBUS:
>  		tcpm_set_state(port, SNK_TRYWAIT, 0);
> -- 
> 2.14.1.342.g6490525c54-goog
>