Hi, I have a piece of software that uses libvlc to playback analog video using V4L2. When stress-testing the software by repeatedly starting and stopping playback, the device I use (TerraTec Cinergy Hybrid Stick [0ccd:00a5]) goes into a very strange state, where it hangs when dequeuing a buffer. This is to where I traced the problem: videobuf_dqbuf() -> stream_next_buffer() -> videobuf_waiton() -> wait_event_interruptible() When the device enters this particular state, the vb->done wait queue is never woken. I was able to trace the cause of that further down to a problem with ISOC transfers from the device no longer working properly: tm6000_irq_callback() -> tm6000_isoc_copy() In this particular state, *all* ISO packet descriptors report an actual transfer length of 0. This in turn seems to be the reason why the wait queue is never woken (buffer_filled() is never called). I've tried to unload and reload the tm6000 module when this issue occurs, but that doesn't help. The problem persists the next time playback is started. The only thing that seems to help is disconnecting and reconnecting the device or, alternatively, reset the USB device using the USBDEVFS_RESET ioctl. I'm wondering whether this is a known problem, or if there is anything I can do to help track this down further. Cheers, Thierry
Attachment:
pgpiekOfFOaSP.pgp
Description: PGP signature
