Hello,
I have same problem. I have found, that C910 alocate whole USB bus and there is 
no possibility
to run two C910 in one USB controller, if you connect second C910 to different 
USB controllers both cameras
are working. 

Regards
Radek Masin
ra...@masin.eu

Dne Ne, 20 Úno 2011 21:57 , Philip Gladstone <phi...@gladstonefamily.net> 
napsal(a):
> I attached two C910s to a small linux box, and ran into the 'Failed to 
> submit URB' problem.
> 
> When I look at the descriptors for this camera, I think I understand the 
> problem. I'm capturing at 5 Mpixels and I'm trying two cameras.
> 
>        VideoStreaming Interface Descriptor:
>          bLength                            38
>          bDescriptorType                    36
>          bDescriptorSubtype                  7 (FRAME_MJPEG)
>          bFrameIndex                        28
>          bmCapabilities                   0x01
>            Still image supported
>          wWidth                           2592
>          wHeight                          1944
>          dwMinBitRate                403107840
>          dwMaxBitRate                806215680
>          dwMaxVideoFrameBufferSize    10077696
>          dwDefaultFrameInterval        1000000
>          bFrameIntervalType                  3
>          dwFrameInterval( 0)           1000000
>          dwFrameInterval( 1)           1333333
>          dwFrameInterval( 2)           2000000
> 
> The video frame size is set to 10Mb. This is surprisingly large as 
> actual frames captured with MJPEG on this camera are typically 500kb or 
> less. When I checked the descriptor for the uncompressed version of the 
> same frame, it came back with the same value of 
> dwMaxVideoFrameBufferSize (effectively 16 bits per pixel). The values 
> for min/max bit rate are (correctly) calculated from the frame intervals 
> and the buffer size.
> 
> Typical JPEG compression gets down to 1 bit per pixel, and 2 bits is 
> very unusual.
> 
> What I want to know is what the impact would be of defining a new QUIRK 
> that overrode the frame buffer size for compressed frames and calculated 
> them at (say) 2 bits per pixel?
> 
> Do other webcams get this right?
> 
> Thanks
> 
> Philip
> 
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