Re: pwc-webcam attached to usb-ohci card blocks on read() indefinitely.

Thomas Winischhofer
2002-03-08T21:27:06Z

> The camera attached to the UHCI-controller running usb-uhci works just
> fine,out the three attached to the OHCI-controllers running usb-ohci don't.
> After a random amount of frames being read from a camera the read()-call
> blocks indefinitely until the device is closed. Next time the v4l-device is
> opened the program can again read frames from the camera but read() always
> blocks after some time.

I can't help, but I have the exact same problem here. Closing the
application (eg. camstream) and re-opening it makes it work again for a
while.

As Carl-Johan said, this happens with or without the pwcx module, so
that's not the problem.

I think it's an ohci problem.

Furthermore, the usb driver(s) behave strangely on
connecting/disconnecting the camera. Sometimes this works flawlessly,
sometimes I get a lot of USB timeout ("usb_control/bulk_msg: timeout")
and/or "USBDEVFS_CONTROL failed dev x rqt 128 rq 6 len 490 ret -110"
messages in the syslog. (Kernel is 2.4.16 and 2.4.18 - no difference)
After a couple of times disconnecting and reconnecting the camera it's
being detected. Since 2.4.18, the camera's LED sometimes is on,
sometimes off - seems quite random.

Even closing the cam application (xawtv, camstream) after the camera
stopped working never results in any error messages in the log, I only
read "pwc: Closing video device: xxx frames received, dumped 0 frames, 0
frames with errors"

Thomas

--
Thomas Winischhofer
Vienna/Austria
mailto:tw@webit.com *** http://www.webit.com/tw