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simon3z / usbtv

Fushicai USBTV007 Audio-Video Grabber
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Cannot use two usbtv devices simultaneously #1

Closed newchief closed 10 years ago

newchief commented 10 years ago

I've compiled this driver as a module for Linux 3.10.25 (I've rewrittten Makefile to achieve that) and for single device, it worked fine. When I connected second device, it cannot start simultaneous grabbing as it fails on ioctl VIDIOC_STREAMON. When two devices are connected, two device files are created in /dev tree: /dev/video0 and /dev/video1. When I start grab live image from either of them, I cannot start grab from the other, i.e. when I start grab from /dev/video1, I can't start grab from /dev/video0 until grab on /dev/video1 is stopped. Similarly, when I start grab on /dev/video0 first, I can't start grab on /dev/video1 until grab on /dev/video0 is stopped. Problem is, I need to grab live image from both devices simultaneously. On userspace, all I see is failed ioctl. The only trace that something went wrong in dmesg is:

ehci-pci 0000:00:1d.7: iso sched full d5e93200

Do you have any idea how to overcome this problem?

simon3z commented 10 years ago

Can you try to check if it happens also with the current code in the kernel? Instead of compiling/using this module just use the one provided by 3.10.25. I have the feeling that the issue you're experiencing is preexisting. If indeed that's the case please try to contact the author of the video implementation (Lubomir Rintel). Sadly I don't have two device to test this myself.

newchief commented 10 years ago

I can't find it in 3.10.25 and AFAIK, usbtv was introduced in 3.11 kernel. I'll try to boot 3.13.1 later during the day.

newchief commented 10 years ago

I booted 3.13.1 and the problem still exists. Then I installed a card with additional USB 2.0 controller to my PC. And this helped - on both kernels 3.13.1 and 3.10.25. Seems like USB 2.0 is not capable to sustain required bandwith. I also tried to connect both usbtv devices to this new controller - no luck, problem occured again. The only valid setup is each usbtv device connected to different controller (one to onboard, one to additional on card).