* Alan Stern wrote: > On Fri, 8 Jul 2011, Thierry Reding wrote: > > > Hi, > > > > I have a device that sometimes enters a strange state in which it keeps > > sending ISO transfers with apparently no content. What happens is that at > > some point the URB callback function keeps getting called, but summing up the > > actual_length field over all iso_frame_desc structures of the URB yields 0, > > which in turn causes the device to no longer respond to userspace. > > > > I'm wondering whether this might be an actual hardware bug. > > Or firmware bug. That seems quite likely. > > > Does anybody know > > whether such behaviour is to be expected, or what an appropriate response > > would be? > > Such behavior should not occur -- but in the real world it _does_ occur > often enough that you shouldn't be very surprised to encounter it. > > Update the firmware, if you can. Complain to the vendor. If nothing > else works, return the device for a refund. Okay, I'll try and contact the vendor then. If they're not responsive, is there anything else I could do? I was thinking something along the lines of marking the corresponding video buffer invalid, so that the error is in fact propagated instead of the driver just stopping to respond. I guess it wouldn't be very good to reset the device from within the driver, but perhaps some userspace application could react to the error code and initiate a reset instead. Thanks, Thierry
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