linux-kernel - Re: [PATCH 3/3] [PATCH v2 3/3] usb: typec: tcpm: charge current handling for sink during hard reset

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Message-ID: <8cdd5aed-4439-40b3-d258-966542a4b1a5@roeck-us.net>
Date:   Sun, 30 Sep 2018 15:05:04 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Badhri Jagan Sridharan <badhri@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Andrzej Hajda <a.hajda@...sung.com>, Li Jun <jun.li@....com>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH 3/3] [PATCH v2 3/3] usb: typec: tcpm: charge current
 handling for sink during hard reset

On 09/28/2018 04:47 PM, Badhri Jagan Sridharan wrote:
> During the initial connect to a non-pd port, sink would hard reset
> twice before deeming that the port partner is non-pd. TCPM sets the
> the charge path to false during the hard reset. This causes unnecessary
> connects/disconnects of charge path and makes port take longer to
> charge from the non-pd ports. Avoid this by not setting the charge path
> to false unless the partner has already identified to be pd capable.
> 
> When partner is a pd port, set the charge path to false in
> SNK_HARD_RESET_SINK_OFF. Set the current limits to default value based
> of CC pull up and resume the charge path when port enters
> SNK_HARD_RESET_SINK_ON.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>

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

> 
> --------
> Changes in V2:
> Based on feedback of jackp@...eaurora.org
> - vsafe_5v_hard_reset flag from tcpc_config is removed
> - Patch only differentiates between pd port partner and non-pd port
> partner
> 
> V1 version of the patch is here:
> https://lkml.org/lkml/2018/9/14/11
> ---
>   drivers/usb/typec/tcpm.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
> index c3ac0e46106b4..c25a69922ee6a 100644
> --- a/drivers/usb/typec/tcpm.c
> +++ b/drivers/usb/typec/tcpm.c
> @@ -3273,7 +3273,8 @@ static void run_state_machine(struct tcpm_port *port)
>   	case SNK_HARD_RESET_SINK_OFF:
>   		memset(&port->pps_data, 0, sizeof(port->pps_data));
>   		tcpm_set_vconn(port, false);
> -		tcpm_set_charge(port, false);
> +		if (port->pd_capable)
> +			tcpm_set_charge(port, false);
>   		tcpm_set_roles(port, port->self_powered, TYPEC_SINK,
>   			       TYPEC_DEVICE);
>   		/*
> @@ -3305,6 +3306,12 @@ static void run_state_machine(struct tcpm_port *port)
>   		 * Similar, dual-mode ports in source mode should transition
>   		 * to PE_SNK_Transition_to_default.
>   		 */
> +		if (port->pd_capable) {
> +			tcpm_set_current_limit(port,
> +					       tcpm_get_current_limit(port),
> +					       5000);
> +			tcpm_set_charge(port, true);
> +		}
>   		tcpm_set_attached_state(port, true);
>   		tcpm_set_state(port, SNK_STARTUP, 0);
>   		break;
>