Hi Andrew,

On Tuesday 15 January 2008, Andrew Perrin wrote:
> On Tue, 15 Jan 2008, Laurent Pinchart wrote:
> > Hi Andrew,
> >
> > On Tuesday 15 January 2008, Andrew Perrin wrote:
> >> I have a quickcam 9000 pro working fine with luvcview, but it gives the
> >> famous "black rectangle" with Skype. This is the latest (166) rev. of
> >> uvcvideo. These messages are in the log when I try:
> >>
> >> Jan 14 19:53:08 joehill kernel: ohci_hcd 0000:00:0b.0: leak ed f74175c0
> >> (#81) state 2
> >> Jan 14 19:53:22 joehill kernel: uvcvideo: Failed to submit URB 0 (-28).
> >> Jan 14 19:53:30 joehill kernel: ohci_hcd 0000:00:0b.0: leak ed f7417600
> >> (#81) state 2
> >
> > -28 is -ENOSPC. It means using the device would exceed the available USB
> > bus bandwidth. If your webcam is plugged into a hub try moving it to a
> > root port. Make sure you're using an EHCI controller.
> >
> > Best regards,
> >
> > Laurent Pinchart
>
> Very interesting, and thanks for your quick reply. Plugging it directly
> into the USB port (instead of through a hub) makes both luvcview *and
> Skype* give a very flickery, but recognizable, image. luvcview dies after
> a few seconds with the result:
>
> Ignoring empty buffer ...
> Ignoring empty buffer ...
> Ignoring empty buffer ...
> Ignoring empty buffer ...
> Unable to dequeue buffer (22).
> Error grabbing
>   Clean Up done Quit
>
> ...while Skype just keeps the flickery image on.  /var/log/syslog
> contains:
>
> usb 1-6: new high speed USB device using ehci_hcd and address 9
> usb 1-6:  configuration #1 chosen from 1 choice
> uvcvideo: Found UVC 1.00 device <unnamed> (046d:0990)
> usb 1-6: USB disconnect, address 9
> usb 1-6: new high speed USB device using ehci_hcd and address 10
> usb 1-6: device descriptor read/all, error -71

Your webcam seem to be very flaky. Failing to respond to the first GET 
DESCRIPTOR request with -71 means serious hardware trouble.

> usb 1-6: new high speed USB device using ehci_hcd and address 11
> usb 1-6: configuration #1 chosen from 1 choice
> uvcvideo: Found UVC 1.00 device <unnamed> (046d:0990)
> uvcvideo: Failed to query (131) UVC control 1 (unit 0) : -71 (exp. 26).
> uvcvideo: Failed to query (131) UVC control 1 (unit 0) : -71 (exp. 26).

You should check your cables. Is your computer in an extremely noisy 
environment (electrically speaking) ? Do you experience the same kind of 
trouble with other USB devices ?

Best regards,

Laurent Pinchart
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