Hi Gerd,
On Sun, 2003-01-12 at 12:51, Gerd Knorr wrote:
> But I think that wouldn't fix the issue. With v4l2 there is no
> difference between /dev/video and /dev/vbi. /dev/vbi is just a
> backward compatibility thing which gives you a /dev/video file handle
> which is in vbi mode by default. If nxtvepg has /dev/vbi open and
> reads from that device, open(/dev/video,O_EXCL) will fail.
>
> The problem isn't that nxtvepg wants exclusive access, it wants just
> play nice and not upset the user running some tv app in parallel by
> switching to another tv channel.
But isn't that the case for many concurrent use cases? A recorder and a
control panel that allows the user to control brightness and contrast
can coexist nicely. I think we should just go for the easy approach
here... Basically, opening /dev/vbi gives you the theoretical option to
do video-capture anyway, so why not just threat it as such?
Of course, apps that don't need it very badly shouldn't use O_EXCL, and
apps that open using O_EXCL for longer than a second should be murdered
('kill' is something different here) instantly, but it's just
theoretical anyway. So the block for the exclusive open wouldn't
(shouldn't) last that long anyway...
Look at it as a rw_sem. ;-).
Ronald
--
Ronald Bultje <rbultje@xxxxxxxxxxxxxxxxxxx>
Linux Video/Multimedia developer
