v4l1 doesn't work anymore with bttv on 2.6.26

v4l1 doesn't work anymore with bttv on 2.6.26

[matthieu castet]

Hi,

This is a copy of the bugreport i did on debian bugtracker : 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=510621


I got a v4l1 application that worked for years.
With the current kernel, it hangs in a state where VIDIOCMCAPTURE always
return -EBUSY.

After some debug, it seems that VIDIOCMCAPTURE fails the first time
because of videobuf_queue_is_busy 'vbuf: busy: buffer #0 mapped'.

Then after that error it does a VIDIOCSYNC on all buffer.
Then every call of VIDIOCMCAPTURE failed because of check_btres
returning -EBUSY.

I don't know what cause the first videobuf_queue_is_busy error.
But for all the other errors I suppose one of the problem is that
VIDIOCSYNC does a STREAMON but never does a STREAMOFF...


Regards,

Matthieu

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Re: v4l1 doesn't work anymore with bttv on 2.6.26

[Trent Piepho]

On Sat, 3 Jan 2009, matthieu castet wrote:
> This is a copy of the bugreport i did on debian bugtracker :
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=510621
>
> I got a v4l1 application that worked for years.
> With the current kernel, it hangs in a state where VIDIOCMCAPTURE always
> return -EBUSY.
>
> After some debug, it seems that VIDIOCMCAPTURE fails the first time
> because of videobuf_queue_is_busy 'vbuf: busy: buffer #0 mapped'.

Around that time frame the bttv driver was converted from having native
v4l1 support to using the v4l1->v4l2 compat module.  The bttv driver
supported a non-standard v4l1 buffer allocation method were there buffers
get allocated or resized in the MCAPTURE ioctl and the v4l1 compat module
doesn't support this.  I bet this is what your problem is.

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