I had a similar problem (recently purchased 3 uvcvideo cameras, hoping
things would "just work"). I have been running 3 Philips pwc cameras
for quite a few years with no real problems, although they are slowly
dying on me.
I also don't think there can be a bandwidth problem at 640x480 using
any palette - it shouldn't saturate a USB2 bus... However, I'm wasn't
smart enough to find out what is wrong using YUYV, so I tried
What I did was to force motion to use MJPEG (using v4l2_palette option
AND a patch), and I also patched the uvcvideo kernel module to add a
needed (by motion) ioctl; have a look at these patches and see if they
work for you: http://www.lavrsen.dk/twiki/bin/view/Motion/UvcvideoMjpegPatch
. They are probably not perfect, but they solved my problem for now of
allowing 3 uvcvideo cameras to work simultaneously.
> From: Louis-David Mitterrand
> Using kernel 2.6.26 on a debian/unstable box and motion 3.2.9-4 I find
> it impossible to start motion with two UVC cameras in the following
> - UBV camera @ 640x480 YUYV + UVC camera @ 640x480 YUYV
> The error:
> Jul 17 18:11:00 sylla kernel: uvcvideo: Failed to submit URB 0 (-28).
> Jul 17 18:11:00 sylla motion:  Error starting stream.
> Jul 17 18:11:00 sylla motion:  VIDIOC_STREAMON: No space left on
> Jul 17 18:11:00 sylla motion:  ioctl(VIDIOCGMBUF) - Error device does
> +not support memory map
> However this configuration works:
> - PWC camera @ 640x480 YUYV + UVC camera @ 960x720 YUYV
> So it doesn't seem to be a USB bandwidth limitation problem (as someone
> on the linux-uvc mailing list suggested).