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Subject: Re: [PATCH v2] platform: cros_ec_debugfs: control uptime information
 request
To:     Gwendal Grignou <gwendal@chromium.org>, groeck@chromium.org,
        bleung@chromium.org, twawrzynczak@chromium.org
Cc:     linux-kernel@vger.kernel.org
References: <20200526185328.231840-1-gwendal@chromium.org>
From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
Message-ID: <09ba7001-6a24-7d96-0328-4ae1d1c62520@collabora.com>
Date:   Thu, 25 Jun 2020 13:53:36 +0200
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Hi Gwendal,

Thank you for your patch.

On 26/5/20 20:53, Gwendal Grignou wrote:
> When EC does not support uptime command (EC_CMD_GET_UPTIME_INFO),
> do not create the uptime sysfs entry point.
> User space application will not probe the file needlessly.
> 
> The EC console log will not contain EC_CMD_GET_UPTIME_INFO anymore.
> 
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>

Applied for 5.9

> ---
>  drivers/platform/chrome/cros_ec_debugfs.c | 24 +++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_debugfs.c b/drivers/platform/chrome/cros_ec_debugfs.c
> index 6ae484989d1f5..303a8c4686f89 100644
> --- a/drivers/platform/chrome/cros_ec_debugfs.c
> +++ b/drivers/platform/chrome/cros_ec_debugfs.c
> @@ -243,6 +243,25 @@ static ssize_t cros_ec_pdinfo_read(struct file *file,
>  				       read_buf, p - read_buf);
>  }
>  
> +static bool cros_ec_uptime_is_supported(struct cros_ec_device *ec_dev)
> +{
> +	struct {
> +		struct cros_ec_command cmd;
> +		struct ec_response_uptime_info resp;
> +	} __packed msg = {};
> +	int ret;
> +
> +	msg.cmd.command = EC_CMD_GET_UPTIME_INFO;
> +	msg.cmd.insize = sizeof(msg.resp);
> +
> +	ret = cros_ec_cmd_xfer_status(ec_dev, &msg.cmd);
> +	if (ret == -EPROTO && msg.cmd.result == EC_RES_INVALID_COMMAND)
> +		return false;
> +
> +	/* Other errors maybe a transient error, do not rule about support. */
> +	return true;
> +}
> +
>  static ssize_t cros_ec_uptime_read(struct file *file, char __user *user_buf,
>  				   size_t count, loff_t *ppos)
>  {
> @@ -445,8 +464,9 @@ static int cros_ec_debugfs_probe(struct platform_device *pd)
>  	debugfs_create_file("pdinfo", 0444, debug_info->dir, debug_info,
>  			    &cros_ec_pdinfo_fops);
>  
> -	debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
> -			    &cros_ec_uptime_fops);
> +	if (cros_ec_uptime_is_supported(ec->ec_dev))
> +		debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
> +				    &cros_ec_uptime_fops);
>  
>  	debugfs_create_x32("last_resume_result", 0444, debug_info->dir,
>  			   &ec->ec_dev->last_resume_result);
>