On Thu, Jul 11, 2013 at 4:24 AM, Johannes Stezenbach <js@xxxxxxxxx> wrote: > There are several cases where the isoc descriptor actual length is > short (< 2892, e.g. 0, 552 or 1928), yet the actual_length for the > whole URB at the end of the line is still 64*2892 -- is that like it should be? Yup, as Alan stated, this is expected behavior. > Also, is it expected that the em28xx doesn't have data to send for > some microframes (for analog video capture e.g. during horizontal > or vertical blank interval)? I guess in the analyzer that should > show as an IN token with no reply instead of DATA[012] replies. > Can you confirm that in the error case there is no IN token at all? > > And another dumb question: Is there another USB video grabber > with different hardware which also uses isoc and works? > E.g. the cx231xx? Or do you think it might have the same missing > microframe issue but copes better with it due to larger > buffer space on the device? I've been actively testing also with an au0828 device (HVR-950q), which has a virtually identical URB completion handler (not shocking, since I copied it from the em28xx driver when I wrote it in 2009). The HVR-950q doesn't exhibit any of the problems described in this thread though (presumably because it has a larger on-chip FIFO). Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
