linux-kernel - Re: [Patch v2 1/3] media: ov5640: add PIXEL

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Date:   Thu, 3 Oct 2019 09:17:14 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Benoit Parrot <bparrot@...com>
Cc:     Hans Verkuil <hverkuil@...all.nl>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Patch v2 1/3] media: ov5640: add PIXEL_RATE control

Hi Benoit,

On Wed, Oct 02, 2019 at 08:51:32AM -0500, Benoit Parrot wrote:
> Add v4l2 controls to report the pixel rates of each mode. This is
> needed by some CSI2 receiver in order to perform proper DPHY
> configuration.
>
> Signed-off-by: Benoit Parrot <bparrot@...com>
> ---
>  drivers/media/i2c/ov5640.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 500d9bbff10b..5198dc887400 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -193,6 +193,9 @@ struct ov5640_mode_info {
>
>  struct ov5640_ctrls {
>  	struct v4l2_ctrl_handler handler;
> +	struct {
> +		struct v4l2_ctrl *pixel_rate;
> +	};

Do you need to wrap this v4l2_ctrl in it's own unnamed struct? Other
controls here declared in this way are clustered and, if I'm not
mistaken, using unnamed struct to wrap them is just a typographically
nice way to convey that. I think your new control could be declared
without a wrapping struct { }.

>  	struct {
>  		struct v4l2_ctrl *auto_exp;
>  		struct v4l2_ctrl *exposure;
> @@ -2194,6 +2197,16 @@ static int ov5640_try_fmt_internal(struct v4l2_subdev *sd,
>  	return 0;
>  }
>
> +static u64 ov5640_calc_pixel_rate(struct ov5640_dev *sensor)
> +{
> +	u64 rate;
> +
> +	rate = sensor->current_mode->vtot * sensor->current_mode->htot;
> +	rate *= ov5640_framerates[sensor->current_fr];
> +
> +	return rate;
> +}
> +

Just to point out this is the -theoretical- pixel rate, and might be
quite different from the one calculated by the clock tree tuning
procedure (which should be updated to match Hugues' latest findings).

>  static int ov5640_set_fmt(struct v4l2_subdev *sd,
>  			  struct v4l2_subdev_pad_config *cfg,
>  			  struct v4l2_subdev_format *format)
> @@ -2233,6 +2246,8 @@ static int ov5640_set_fmt(struct v4l2_subdev *sd,
>  	if (mbus_fmt->code != sensor->fmt.code)
>  		sensor->pending_fmt_change = true;
>
> +	__v4l2_ctrl_s_ctrl_int64(sensor->ctrls.pixel_rate,
> +				 ov5640_calc_pixel_rate(sensor));
>  out:
>  	mutex_unlock(&sensor->lock);
>  	return ret;
> @@ -2657,6 +2672,13 @@ static int ov5640_init_controls(struct ov5640_dev *sensor)
>  	/* we can use our own mutex for the ctrl lock */
>  	hdl->lock = &sensor->lock;
>
> +	/* Clock related controls */
> +	ctrls->pixel_rate =
> +		v4l2_ctrl_new_std(hdl, ops,

If you like it better, this could fit in 1 line

	ctrls->pixel_rate = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_PIXEL_RATE,
					      0, INT_MAX, 1,
					      ov5640_calc_pixel_rate(sensor)

Thanks
   j

> +				  V4L2_CID_PIXEL_RATE, 0, INT_MAX, 1,
> +				  ov5640_calc_pixel_rate(sensor));


> +	ctrls->pixel_rate->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
>  	/* Auto/manual white balance */
>  	ctrls->auto_wb = v4l2_ctrl_new_std(hdl, ops,
>  					   V4L2_CID_AUTO_WHITE_BALANCE,
> @@ -2816,6 +2838,9 @@ static int ov5640_s_frame_interval(struct v4l2_subdev *sd,
>  		sensor->frame_interval = fi->interval;
>  		sensor->current_mode = mode;
>  		sensor->pending_mode_change = true;
> +
> +		__v4l2_ctrl_s_ctrl_int64(sensor->ctrls.pixel_rate,
> +					 ov5640_calc_pixel_rate(sensor));
>  	}
>  out:
>  	mutex_unlock(&sensor->lock);
> --
> 2.17.1
>

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