Re: [Linux-uvc-devel] Logitech QC 9000 camera on ARM platform

[Laurent P. <lau...@id...>]

Hi Sascha,

On Wednesday 10 February 2010 12:25:06 Sascha Lumma wrote:
> Hi all,
> 
> I've a problem with that setup and it's quite difficult to explain. I
> searched on the Internet for that issue but I found nothing appropriate,
> hence I will try to explain it here...
> 
> I am using a Logitech QC Pro 9000 connected with a beagleboard (OMAP35 -
> ARM Cortex 8 & TMS320C64x DSP) running Angstrom (kernel 2.6.29). That
> setup is running fine so far and I can use all of the required features
> (fps from ~10 to ~15 with VGA resolution). But the frames I get from the
> camera contain some errors (stripes with inverted colors) randomly.
> Unfortunately, there is no regularity (position and length) and it
> happens not in all frames. I am using memory mapped buffers to get the
> frames. The first idea rising up in my mind is it could be caused by a
> race condition somewhere, but it's only an idea.
> 
> I tried already two other cameras (but same type) and other beagleboards
> as well, no change. Furthermore, I compiled my program on an 686-Box and
> it is working there without that errors (unfortunately with a newer
> kernel 2.6.31 and 32). Were there related Issues in 2.6.29?

That kind of problem is usually caused by lost USB packets. There's not much 
the driver can do. It could be anything from a USB controller driver bug to 
bad USB cable, through a USB bandwidth limitation on the OMAP35xx processor 
(in that case you could try capturing in MJPEG instead of YUYV) or a board 
routing issue.

-- 
Regards,

Laurent Pinchart