linux-kernel - Re: [RFC 4/5] media: i2c: ov5670: Report the camera location

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Message-ID: <20190815070420.GL6133@paasikivi.fi.intel.com>
Date:   Thu, 15 Aug 2019 10:04:20 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Jacopo Mondi <jacopo@...ndi.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        "open list:MEDIA INPUT INFRASTRUCTURE (V4L/DVB)" 
        <linux-media@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC 4/5] media: i2c: ov5670: Report the camera location

Hi Jacopo,

On Wed, Aug 14, 2019 at 10:28:14PM +0200, Jacopo Mondi wrote:
> The camera location is retrieved from the firmware interface parsing
> the "location" device property and reported through the read-only
> V4L2_CID_LOCATION control.
> 
> Signed-off-by: Jacopo Mondi <jacopo@...ndi.org>
> ---
>  drivers/media/i2c/ov5670.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov5670.c b/drivers/media/i2c/ov5670.c
> index 041fcbb4eebd..1446aef1fc1e 100644
> --- a/drivers/media/i2c/ov5670.c
> +++ b/drivers/media/i2c/ov5670.c
> @@ -2059,10 +2059,12 @@ static const struct v4l2_ctrl_ops ov5670_ctrl_ops = {
>  /* Initialize control handlers */
>  static int ov5670_init_controls(struct ov5670 *ov5670)
>  {
> +	struct i2c_client *client = v4l2_get_subdevdata(&ov5670->sd);
>  	struct v4l2_ctrl_handler *ctrl_hdlr;
>  	s64 vblank_max;
>  	s64 vblank_def;
>  	s64 vblank_min;
> +	u32 location;
>  	s64 exposure_max;
>  	int ret;
>  
> @@ -2124,6 +2126,15 @@ static int ov5670_init_controls(struct ov5670 *ov5670)
>  				     ARRAY_SIZE(ov5670_test_pattern_menu) - 1,
>  				     0, 0, ov5670_test_pattern_menu);
>  
> +	ret = device_property_read_u32(&client->dev, "location", &location);
> +	if (!ret) {
> +		v4l2_ctrl_new_std(ctrl_hdlr, &ov5670_ctrl_ops,
> +				  V4L2_CID_LOCATION, V4L2_LOCATION_FRONT,
> +				  V4L2_LOCATION_BACK, 1,
> +				  location == V4L2_LOCATION_FRONT ?

To do this, you'll need to document that the control values match DT
binding values. I don't think that's there currently.

A switch would be nicer, to check that the value that is not front is
something else meaningful. Otherwise I wouldn't create the control at all.

A helper function for drivers to use would be nice.

> +				  V4L2_LOCATION_FRONT : V4L2_LOCATION_BACK);
> +	}
> +
>  	if (ctrl_hdlr->error) {
>  		ret = ctrl_hdlr->error;
>  		goto error;

-- 
Regards,

Sakari Ailus
sakari.ailus@...ux.intel.com