SOLVED [linux-dvb] cx88[0]/2: cx8802_restart_queue: queue is empty

[Adam Nielsen]

> every 30 seconds or so some data is dropped (enough to corrupt the
> video and make the sound drop out for a second) and while this happens
> my kernel logs are filled with these messages
> Sep  4 16:41:06 [kernel] [4295039.887000] cx88[0]/2: cx8802_restart_queue
> Sep  4 16:41:06 [kernel] [4295039.887000] cx88[0]/2: cx8802_restart_queue: queue is empty
> Sep  4 16:41:06 [kernel] [4295040.064000] cx88[0]/2: queue is empty - first active
> Sep  4 16:41:06 [kernel] [4295040.064000] cx88[0]/2: cx8802_start_dma w: 0, h: 0, f: 2
> Sep  4 16:41:06 [kernel] [4295040.064000] cx88[0]/2: setting the interrupt mask
> Sep  4 16:41:06 [kernel] [4295040.064000] cx88[0]/2: [c5247560/14] cx8802_buf_queue - first active

Well, quite by chance, I figured out what the problem was.  I was
recording the stream to disk, and the disk happened to be an old IDE
one...and for some reason DMA hadn't been automatically enabled.

I noticed that while recording DVB streams the whole server would lock
up for half a second or so every 15 seconds, and this coincided exactly
with the writes out to the disk.  A quick check using hdparm verified
that the drive was operating in PIO mode, and once I enabled UDMA the
messages disappeared from my logs and the corrupt sections in the video
went away!  Yay :-)

Hopefully this will help someone solve a similar issue in the future...

Cheers,
Adam.