linux-kernel - Re: [PATCH v2 3/4] platform/chrome: cros_ec_typec: Configure muxes at start of port update

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Message-ID: <YgrzbQViMLRTC4XB@google.com>
Date:   Mon, 14 Feb 2022 16:27:25 -0800
From:   Benson Leung <bleung@...gle.com>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        "open list:CHROMEOS EC USB TYPE-C DRIVER" 
        <chrome-platform@...ts.linux.dev>
Subject: Re: [PATCH v2 3/4] platform/chrome: cros_ec_typec: Configure muxes
 at start of port update

Hi Prashant,

On Tue, Feb 08, 2022 at 06:47:22PM +0000, Prashant Malani wrote:
> There are situations where the mux state reported by the Embedded
> Controller (EC), might lag the partner "connected" state. So, the mux
> state might still suggest that a partner is connected, while the PD
> "connected" state, being in Try.SNK (for example) suggests that the
> partner is disconnected.
> 
> In such a scenario, we will end up sending a disconnect command to the
> mux driver, followed by a connect command, since the mux is configured
> later. Avoid this by configuring the mux before
> registering/disconnecting a partner.
> 
> Signed-off-by: Prashant Malani <pmalani@...omium.org>

Reviewed-by: Benson Leung <bleung@...omium.org>


> ---
> 
> Changes in v2:
> - Change return at end of port_update() to just return 0.
> 
>  drivers/platform/chrome/cros_ec_typec.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 3d34ece7f790..3019e29f200d 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -965,6 +965,11 @@ static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Update the switches if they exist, according to requested state */
> +	ret = cros_typec_configure_mux(typec, port_num, &resp);
> +	if (ret)
> +		dev_warn(typec->dev, "Configure muxes failed, err = %d\n", ret);
> +
>  	dev_dbg(typec->dev, "Enabled %d: 0x%hhx\n", port_num, resp.enabled);
>  	dev_dbg(typec->dev, "Role %d: 0x%hhx\n", port_num, resp.role);
>  	dev_dbg(typec->dev, "Polarity %d: 0x%hhx\n", port_num, resp.polarity);
> @@ -980,12 +985,7 @@ static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)
>  	if (typec->typec_cmd_supported)
>  		cros_typec_handle_status(typec, port_num);
>  
> -	/* Update the switches if they exist, according to requested state */
> -	ret = cros_typec_configure_mux(typec, port_num, &resp);
> -	if (ret)
> -		dev_warn(typec->dev, "Configure muxes failed, err = %d\n", ret);
> -
> -	return ret;
> +	return 0;
>  }
>  
>  static int cros_typec_get_cmd_version(struct cros_typec_data *typec)
> -- 
> 2.35.0.263.gb82422642f-goog
> 
> 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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