linux-kernel - Re: [PATCH 10/11] staging: typec: tcpm: Do not send PING msgs in TCPM

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Date:   Sun, 27 Aug 2017 10:27:19 -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 10/11] staging: typec: tcpm: Do not send PING msgs in TCPM

On Sat, Aug 26, 2017 at 11:52:00PM -0700, Badhri Jagan Sridharan wrote:
> PING messages are used to monitor the connect/disconnect.
> However, when PD is carried over CC, so this is not required.
> 
> Also, the spec does not clearly say if PD is possible when
> Type-c is connected to Type-A/B. So, removing sending
> PING messages altogether.
> 
> Signed-off-by: Badhri Jagan Sridharan <Badhri@...gle.com>

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

> ---
>  drivers/staging/typec/tcpm.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index a7da609006f5..9e0111dea7c4 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -2335,14 +2335,11 @@ static void run_state_machine(struct tcpm_port *port)
>  		 * - The system is not operating in PD mode
>  		 * or
>  		 * - Both partners are connected using a Type-C connector
> -		 *   XXX How do we know that ?
> +		 *
> +		 * There is no actual need to send PD messages since the local
> +		 * port type-c and the spec does not clearly say whether PD is
> +		 * possible when type-c is connected to Type-A/B
>  		 */
> -		if (port->pwr_opmode == TYPEC_PWR_MODE_PD &&
> -		    !port->op_vsafe5v) {
> -			tcpm_pd_send_control(port, PD_CTRL_PING);
> -			tcpm_set_state_cond(port, SRC_READY,
> -					    PD_T_SOURCE_ACTIVITY);
> -		}
>  		break;
>  	case SRC_WAIT_NEW_CAPABILITIES:
>  		/* Nothing to do... */
> -- 
> 2.14.1.342.g6490525c54-goog
>