Re: [PATCH 3/3] [media] cobalt: Use v4l2_calc_timeperframe helper

Hans Verkuil
2017-03-30T13:42:57Z

Hi Jose,

On 21/03/17 12:49, Jose Abreu wrote:
> Currently, cobalt driver always returns 60fps in g_parm.
> This patch uses the new v4l2_calc_timeperframe helper to
> calculate the time per frame value.

I can verify that g_parm works, so:

Tested-by: Hans Verkuil <hans.verkuil@cisco.com>

However, the adv7604 pixelclock detection resolution is only 0.25 MHz, so it
can't tell the difference between 24 and 23.97 Hz. I can't set the new
V4L2_DV_FL_CAN_DETECT_REDUCED_FPS flag there.

It might be possible to implement this for the adv7842 receiver, I think that
that hardware is much more precise.

I would have to try this, but that will have to wait until Friday next week.

Regards,

Hans

>
> Signed-off-by: Jose Abreu <joabreu@synopsys.com>
> Cc: Carlos Palminha <palminha@synopsys.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Cc: linux-media@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
> drivers/media/pci/cobalt/cobalt-v4l2.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/pci/cobalt/cobalt-v4l2.c b/drivers/media/pci/cobalt/cobalt-v4l2.c
> index def4a3b..25532ae 100644
> --- a/drivers/media/pci/cobalt/cobalt-v4l2.c
> +++ b/drivers/media/pci/cobalt/cobalt-v4l2.c
> @@ -1076,10 +1076,15 @@ static int cobalt_subscribe_event(struct v4l2_fh *fh,
>
> static int cobalt_g_parm(struct file *file, void *fh, struct v4l2_streamparm *a)
> {
> + struct cobalt_stream *s = video_drvdata(file);
> + struct v4l2_fract fps;
> +
> if (a->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
> return -EINVAL;
> - a->parm.capture.timeperframe.numerator = 1;
> - a->parm.capture.timeperframe.denominator = 60;
> +
> + fps = v4l2_calc_timeperframe(&s->timings);
> + a->parm.capture.timeperframe.numerator = fps.numerator;
> + a->parm.capture.timeperframe.denominator = fps.denominator;
> a->parm.capture.readbuffers = 3;
> return 0;
> }
>