linux-kernel - Re: [PATCH v1 07/11] ti948: Add sysfs node for alive attribute

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Message-ID: <20190611181144.GV5016@pendragon.ideasonboard.com>
Date:   Tue, 11 Jun 2019 21:11:44 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Michael Drake <michael.drake@...ethink.co.uk>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...ts.codethink.co.uk,
        Patrick Glaser <pglaser@...la.com>, Nate Case <ncase@...la.com>
Subject: Re: [PATCH v1 07/11] ti948: Add sysfs node for alive attribute

Hi Michael,

Thank you for the patch.

On Tue, Jun 11, 2019 at 03:04:08PM +0100, Michael Drake wrote:
> This may be used by userspace to determine the state
> of the device.

Why is this needed ? Userspace shouldn't even be aware that this device
exists.

> Signed-off-by: Michael Drake <michael.drake@...ethink.co.uk>
> Cc: Patrick Glaser <pglaser@...la.com>
> Cc: Nate Case <ncase@...la.com>
> ---
>  drivers/gpu/drm/bridge/ti948.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti948.c b/drivers/gpu/drm/bridge/ti948.c
> index b5c766711c4b..b624eaeabb43 100644
> --- a/drivers/gpu/drm/bridge/ti948.c
> +++ b/drivers/gpu/drm/bridge/ti948.c
> @@ -412,6 +412,16 @@ static void ti948_alive_check(struct work_struct *work)
>  	schedule_delayed_work(&ti948->alive_check, TI948_ALIVE_CHECK_DELAY);
>  }
>  
> +static ssize_t alive_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct ti948_ctx *ti948 = ti948_ctx_from_dev(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%u\n", (unsigned int)ti948->alive);
> +}
> +
> +static DEVICE_ATTR_RO(alive);
> +
>  static int ti948_pm_resume(struct device *dev)
>  {
>  	struct ti948_ctx *ti948 = ti948_ctx_from_dev(dev);
> @@ -614,17 +624,31 @@ static int ti948_probe(struct i2c_client *client,
>  
>  	i2c_set_clientdata(client, ti948);
>  
> +	ret = device_create_file(&client->dev, &dev_attr_alive);
> +	if (ret) {
> +		dev_err(&client->dev, "Could not create alive attr\n");
> +		return ret;
> +	}
> +
>  	ret = ti948_pm_resume(&client->dev);
> -	if (ret != 0)
> -		return -EPROBE_DEFER;
> +	if (ret != 0) {
> +		ret = -EPROBE_DEFER;
> +		goto error;
> +	}
>  
>  	dev_info(&ti948->i2c->dev, "End probe (addr: %x)\n", ti948->i2c->addr);
>  
>  	return 0;
> +
> +error:
> +	device_remove_file(&client->dev, &dev_attr_alive);
> +	return ret;
>  }
>  
>  static int ti948_remove(struct i2c_client *client)
>  {
> +	device_remove_file(&client->dev, &dev_attr_alive);
> +
>  	return ti948_pm_suspend(&client->dev);
>  }
>  

-- 
Regards,

Laurent Pinchart