On Sunday 03 March 2013 09:57:14 Devin Heitmueller wrote: > On Sun, Mar 3, 2013 at 4:37 AM, Rémi Denis-Courmont <remi@xxxxxxxxxx> wrote: > > Hello, > > > > Trying to use USERPTR buffers with UVC, user space gets stuck either in > > poll(POLLIN) or in ioctl(VIDIOC_DQBUF). It seems the UVC driver never ever > > returns a frame in USERPTR mode. The symptoms are identical with kernel > > versions 3.6, 3.7 and 3.8. I also tested 3.2, but it did not support > > USERPTR. > > > > Tested hardware was Logitech HD Pro Webcam C920 with YUY2 pixel format. > > The same hardware and the same driver work fine with MMAP buffers. > > The same USERPTR userspace code works fine with the vivi test device... > > > > Did any have any better luck? I've just tested USERPTR with a Logitech C905 on a 3.7.10 kernel using yavta without any issue. > Hi Remi, > > I've used userptr mode with the C920 on an ARM platform (with YUYV mode and > not MPEG). It's worth noting that there is actually a bug I hit where if > the memory you pass is not aligned on a page boundary then you will get > garbage video. I have a fix or this but haven't submitted it upstream yet. Please submit it at some point :-) Is it a uvcvideo issue or a videobuf2 issue ? > So it should work, aside from the bug I found. > > Have you tried testing with v42l-ctl's streaming command? That would help > identify whether it's something special about your code or whether it's the > driver. Don't get me wrong, it's almost certainly a driver issue in either > case, but it would help narrow down the issue if you're using v4l2-ctl as > that app is really simple and readily available to the driver developers. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
