usb or video4linux problem

[(no name)]

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I send a mail few days ago about a problem with a usb webcam (Dlink
DCS100). I see the same thing with various webcam apps (gnomemeeting,
gqcam, camstream, xawtv, ...). So clearly it's not a user-level problem.
It can be a hardware one but i'm convinced it is not (or in the OHCI
chip in my toshiba satellite 2520cds).

With all app I can see the stream but suddenly it freezes.
Because of the following output from xawtv when the problem occurs:

v4l: timeout (got SIGALRM), hardware/driver problems?
ioctl: VIDIOCSYNC(0): Appel syst=E8me interrompu

I have checked out the code and the interesting part in drv1-v4l.c is :

    alarms=3D0;
    alarm(SYNC_TIMEOUT);

 retry:
    if (-1 =3D=3D (rc =3D xioctl(h->fd,VIDIOCSYNC,h->buf_v4l+frame))) {
   if (errno =3D=3D EINTR && !alarms)
       goto retry;
    }

=46rom which I conclude that SYNC_TIMEOUT could be to small. The value is
3 secondes which seems to be quite enough. To be sure I've tried with 30
and got the same thing.

So It's a justified timeout because the nextframe will never be there.
usbview sees the webcam before and after the problem.
Restarting the app is enough to get the stream.=20

I'm convinced that it's a problem with OHCI.
I think it's a soft problem because I can trigger it with cpu/io
activity.

What can I do to go further ?

Christophe

--=20
Christophe Barb=E9 <[e-mail]>
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