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

Jose Abreu
2017-03-31T09:00:35Z

Hi Hans,

On 30-03-2017 14:42, Hans Verkuil wrote:
> 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.

Thanks! Yes, maybe its better to test with a different receiver,
if it has more precision then its great. Let me know if you need
any help :)

Best regards,
Jose Miguel Abreu

>
> 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;
>> }
>>