On Mon June 4 2012 21:50:46 Ezequiel Garcia wrote:
> On Mon, Jun 4, 2012 at 5:47 AM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> >
> >> Would you care to explain me this change in your patch?
> >> + set_bit(V4L2_FL_USE_FH_PRIO, &dev->vdev.flags);
> >
> > See Documentation/video4linux/v4l2-framework.txt:
> >
> > "flags: optional. Set to V4L2_FL_USE_FH_PRIO if you want to let the framework
> > handle the VIDIOC_G/S_PRIORITY ioctls. This requires that you use struct
> > v4l2_fh. Eventually this flag will disappear once all drivers use the core
> > priority handling. But for now it has to be set explicitly."
> >
>
> So, by using v4l2_fh and setting V4L2_FL_USE_FH_PRIO, I can have
> {g,s}_priority ioctls for free, right?
Yes.
> As far as I can see __video_do_ioctl checks if the ioctl is possible, like this:
>
> 520 if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) {
> 521 vfh = file->private_data;
> 522 use_fh_prio = test_bit(V4L2_FL_USE_FH_PRIO, &vfd->flags);
> 523 }
> 524
> 525 if (use_fh_prio)
> 526 ret_prio = v4l2_prio_check(vfd->prio, vfh->prio);
And V4L2_FL_USES_V4L2_FH is set by v4l2_fh_init() (called by v4l2_fh_open()).
Regards,
Hans
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