On Monday 15 June 2009 21:51:13 Mauro Carvalho Chehab wrote:
> Em Mon, 15 Jun 2009 16:02:40 +0200
> Hans Verkuil <hverkuil@xxxxxxxxx> escreveu:
>
> >
> > The sticking point for me is that warning since for cx18/ivtv it is OK if you
> > get something else then you specified (since it is a starting index meant to
> > distinguish mpeg encoders from raw video inputs, from mpeg decoders, etc.).
> >
> > So generating a warning for those two drivers is not correct.
> Ok.
>
> > Perhaps we should add a V4L2_FL_KNUM_OFFSET flag for the struct video_device
> > flags field that tell the register function that 'nr' should be interpreted
> > as a kernel number offset, and not as a preferred number. In the latter case
> > you generate a warning, in the first case you don't.
>
> Hmm... V4L2_FL_KNUM_OFFSET seems a too obfuscated name. Also, such flag would
> be needed by just the register function, so, IMO, a parameter would work better.
That was the idea with the video_register_device_range() proposal. I don't want
to modify all existing video_register_device() calls.
> Also, am I wrong or is there anything wrong with the flags?
>
> The only place I'm seeing this being used is here:
>
> $ grep 'vdev->flags' v4l/*.[ch]
> v4l/v4l2-dev.c: set_bit(V4L2_FL_UNREGISTERED, &vdev->flags);
>
> It is being set, but no code seems to actually test for it. So, IMO, we can
> just remove this field.
No, it is used a lot through the video_is_unregistered() inline in
media/v4l2-dev.h.
>
> One alternative would be to implement it as something like:
>
> +int __must_check __video_register_device(struct video_device *vdev,
> + const int type, const int nr, int warn_if_skip);
>
> #define video_register_device(vdev, type, nr) __video_register_device(vdev, type, nr, 0)
Hmm, that's an option. Although I'd make it a static inline:
static inline int __must_check video_register_device(...)
{
return __video_register_device(vdev, type, nr, 1);
}
Regards,
Hans
>
> >
> > I think it isn't a bad idea to use a flag. It reflects the two possible use
> > cases: one for drivers that create multiple video (or vbi) devices and use the
> > kernel number to reflect the purpose of each video device, and the other where
> > the user wants a specific kernel number. In the latter case the driver creates
> > a single video device.
> >
> > I don't want to see a lot of kernel warnings each time an ivtv or cx18 driver
> > is loaded. Those warnings do not apply to those drivers.
> >
> > BTW: please note that my v4l-dvb-misc tree contains a patch to clean up the
> > comments/variable names in v4l2-dev.c. You might want to pull that in first.
>
> Please see my comments for your v4l-dvb-misc tree pull request. Let's first
> work on that changeset, and then we can discuss better about the warning issue.
>
> > Regards,
> >
> > Han
>
>
>
> Cheers,
> Mauro
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>
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom
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