Re: [PATCH 1/4] media: ov5640: fix resolution update

[jacopo mondi <jacopo@jmondi.org>]

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Hi Sam,
   thanks for the patch, I see the same issue you reported, but I
think this patch can be improved.

(expanding the Cc list to all people involved in recent ov5640
developemts, not just for this patch, but for the whole series to look
at. Copying names from another series cover letter, hope it is
complete.)

On Mon, Oct 08, 2018 at 11:47:59PM -0700, Sam Bobrowicz wrote:
> set_fmt was not properly triggering a mode change when
> a new mode was set that happened to have the same format
> as the previous mode (for example, when only changing the
> frame dimensions). Fix this.
>
> Signed-off-by: Sam Bobrowicz <sam@elite-embedded.com>
> ---
>  drivers/media/i2c/ov5640.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index eaefdb5..5031aab 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -2045,12 +2045,12 @@ static int ov5640_set_fmt(struct v4l2_subdev *sd,
>  		goto out;
>  	}
>
> -	if (new_mode != sensor->current_mode) {
> +
> +	if (new_mode != sensor->current_mode ||
> +	    mbus_fmt->code != sensor->fmt.code) {
> +		sensor->fmt = *mbus_fmt;
>  		sensor->current_mode = new_mode;
>  		sensor->pending_mode_change = true;
> -	}
> -	if (mbus_fmt->code != sensor->fmt.code) {
> -		sensor->fmt = *mbus_fmt;
>  		sensor->pending_fmt_change = true;
>  	}

How I did reproduce the issue:

# Set 1024x768 on ov5640 without changing the image format
# (default image size at startup is 640x480)
$ media-ctl --set-v4l2 "'ov5640 2-003c':0[fmt:UYVY2X8/1024x768 field:none]"
  sensor->pending_mode_change = true; //verified this flag gets set

# Start streaming, after having configured the whole pipeline to work
# with 1024x768
$  yavta -c10 -n4 -f UYVY -s 1024x768 /dev/video4
   Unable to start streaming: Broken pipe (32).

# Inspect which part of pipeline validation went wrong
# Turns out the sensor->fmt field is not updated, and when get_fmt()
# is called, the old one is returned.
$ media-ctl -e "ov5640 2-003c" -p
  ...
  [fmt:UYVY8_2X8/640x480@1/30 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
                 ^^^ ^^^

So yes, sensor->fmt is not udapted as it should be when only image
resolution is changed.

Although I still see value in having two separate flags for the
'mode_change' (which in ov5640 lingo is resolution) and 'fmt_change' (which
in ov5640 lingo is the image format), and write their configuration to
registers only when they get actually changed.

For this reasons I would like to propse the following patch which I
have tested by:
1) changing resolution only
2) changing format only
3) change both

What do you and others think?

Thanks
  j

diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
index eaefdb5..e392b9d 100644
--- a/drivers/media/i2c/ov5640.c
+++ b/drivers/media/i2c/ov5640.c
@@ -2020,6 +2020,7 @@ static int ov5640_set_fmt(struct v4l2_subdev *sd,
        struct ov5640_dev *sensor = to_ov5640_dev(sd);
        const struct ov5640_mode_info *new_mode;
        struct v4l2_mbus_framefmt *mbus_fmt = &format->format;
+       struct v4l2_mbus_framefmt *fmt;
        int ret;

        if (format->pad != 0)
@@ -2037,22 +2038,19 @@ static int ov5640_set_fmt(struct v4l2_subdev *sd,
        if (ret)
                goto out;

-       if (format->which == V4L2_SUBDEV_FORMAT_TRY) {
-               struct v4l2_mbus_framefmt *fmt =
-                       v4l2_subdev_get_try_format(sd, cfg, 0);
+       if (format->which == V4L2_SUBDEV_FORMAT_TRY)
+               fmt = v4l2_subdev_get_try_format(sd, cfg, 0);
+       else
+               fmt = &sensor->fmt;

-               *fmt = *mbus_fmt;
-               goto out;
-       }
+       *fmt = *mbus_fmt;

        if (new_mode != sensor->current_mode) {
                sensor->current_mode = new_mode;
                sensor->pending_mode_change = true;
        }
-       if (mbus_fmt->code != sensor->fmt.code) {
-               sensor->fmt = *mbus_fmt;
+       if (mbus_fmt->code != sensor->fmt.code)
                sensor->pending_fmt_change = true;
-       }
 out:
        mutex_unlock(&sensor->lock);
        return ret;

>  out:
> --
> 2.7.4
>

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