On Wed, Jan 04, 2006 at 12:23:41PM -0800, wrote:
> I have a Logitech QuickCam Orbit (USB ID 046d:08b5), which I'm trying to
> use with Fedora Core 4's heavily patched 2.6.14 kernel
> (2.6.14-1.1653_FC4, also failed with an older FC4 kernel). It fails on
> two very different system hardware configurations. I've tried both the
> Fedora-supplied pwc driver and 10.0.9. This same camera worked fine,
> with both versions of the driver and on more than one computer, under
> FC3.
>
> Under FC4, I get tons of buffer underflow messages ("pwc Frame buffer
> underflow (<something> bytes)"; discarded". The driver never seems to
> manage to put together a complete frame, and the userland application
> typically hangs until it gets a hard kill (tested with gnomemeeting,
> ffmpeg, and probably others; I forget).
>
> On both of the computers I've tested it on, the camera is the only
> device on the bus other than, in one case, a hub.
>
[..]
> I have a feeling that the old USB code used to "clean up" the
> isochronous stream in some way before the pwc driver saw it, and the new
> code doesn't... but I have no idea whether the problem is that Fedora
> has broken the USB subsystem, or 2.6.14 in general is broken, or the
> driver is making improper assumptions, or what... and certainly I have
> no idea how to fix it.
Can your try an official linux kernel ? 2.6.13, 2.6.14, 2.6.15 ? Perhaps some
changes in the usb stack for your chipset made these errors ? I'use only home
made kernel 2.6.13, 2.6.14, and with an intel chipset (uhci).
Luc
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