I have a bunch of usb cards that have moschip ehci controllers in them that have a silicon bug that causes the microframe counter to be updated before the frame counter here's the details of the patch:
This patch (as1489) works around a hardware bug in MosChip EHCI controllers. Evidently when one of these controllers increments the frame-index register, it changes the three low-order bits (the microframe counter) before changing the higher order bits (the frame counter). If the register is read at just the wrong time, the value obtained is too low by 8. When the appropriate quirk flag is set, we work around this problem by reading the frame-index register a second time if the first value's three low-order bits are all 0. This gives the hardware a chance to finish updating the register, yielding the correct value. This prevents the main problem of the driver crashing but there is a lingering issue that I believe is due to the uvcvideo driver's handling of the patch. The video stream eventually seems to "loose sync" is the best way i can describe it....I've posted a video of the problem on youtube here: http://www.youtube.com/watch?v=W-gAHa0zL7A There are 12 instances of guvcvideo running, 3 or 4 of the cameras have developed the issue after about 12 hours. When the glitch happens, the bottom portion of the image freezes and the flashing segments at the top are still updating but clearly something is messed up. Any thoughts? -Jason -- /* Jason Pitt PhD 206.667.5603 Roth Lab jp...@fhcrc.org Basic Sciences Division Fred Hutchinson Cancer Research Center 1100 Fairview Ave N A3-135 Seattle, WA 98109 */ _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
