https://bugzilla.kernel.org/show_bug.cgi?id=207045 --- Comment #1 from Julian Meyer (jucmeyer@xxxxxxxx) --- Narrowing this issue further, it seems that if the max video frame size is less than the max video transfer size, it works, but if it's over the max video transfer size, it does not work: WORKING (low res) ------- bmHint 0x01 bFormatIndex 1 bFrameIndex 3 dwFrameInterval 333333 wKeyFrameRate 0 wPFrameRate 0 wCompQuality 0 wCompWindowSize 0 wDelay 32 dwMaxVideoFrameSize 50688 dwMaxPayloadTransferSize 129024 NOT WORKING (high res) ----------- bmHint 0x01 bFormatIndex 1 bFrameIndex 1 dwFrameInterval 333333 wKeyFrameRate 0 wPFrameRate 0 wCompQuality 0 wCompWindowSize 0 wDelay 32 dwMaxVideoFrameSize 614400 dwMaxPayloadTransferSize 119296 In the non-working case, first, I see this in the log when it gets set up: [41790.164920] uvcvideo: Allocated 5 URB buffers of 32x512 bytes each. I'm not sure why it's 5, but we know that each URB buffer is 16384 bytes large and then I see this message in the log a bunch: [41790.355807] uvcvideo: payload size is: 131072, max is: 119296 My guess here is that it's sending dwMaxVideoFrameSize and assuming that is the dwMaxPayloadTransferSize. So, it tries to send 614400 in a single payload (not sure about the terminology here), but the buffer is only 119296 bytes large. This means that it would not work if the max video frame size is greater than the max payload transfer size (buffer "overflows" and UVC assumes it's the end of the frame), but it would work if the maxVideoFrameSize is smaller than dwMaxPayloadTransferSize. Also, it makes sense because if I run it at a high resolution, the bottom 1/3 of the picture is cut off/corrupted whereas the top part is just fine. In this case, dwMaxVideoFrameSize is probably about 30% larger than dwMaxPayloadTransferSize. -- You are receiving this mail because: You are watching the assignee of the bug.
