[alsa-devel] BUG: USB audio discontinuities with 'UHCI: implement new semantics for URB_ISO_ASAP'

[Alan Stern]

On Wed, 8 May 2013, Joe Rayhawk wrote:

> For what it's worth, the following -stable patch
> 
> "ALSA: USB: adjust for changed 3.8 USB API"
> c75c5ab575af7db707689cdbb5a5c458e9a034bb
> 
> fixes the discontinuous playback on period sizes between 139 and 192,
> but the discontinuous playback on period sizes between 48 and 138 has
> been replaced by rather worse kernel blocking and kernel errors:
> 
> jrayhawk at richardiv:~$ sudo tail -F -n 0 /var/log/kern.log &
> [1] 4490
> jrayhawk at richardiv:~$ time perl -e 'print pack "H*", "00FF" x 2048' | aplay --period-size=192 -r 48000 -f S16_LE -c2 -D hw:0,0
> Playing raw data 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
> 
> real	0m0.053s
> user	0m0.008s
> sys	0m0.000s
> jrayhawk at richardiv:~$ time perl -e 'print pack "H*", "00FF" x 2048' | aplay --period-size=48 -r 48000 -f S16_LE -c2 -D hw:0,0
> Playing raw data 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
> May  8 17:01:56 richardiv kernel: [ 1680.923474] cannot submit urb (err = -18)
> May  8 17:01:56 richardiv kernel: [ 1680.924472] cannot submit urb (err = -18)
> 
> real	0m10.023s
> user	0m0.008s
> sys	0m0.004s

I don't know if you want to investigate this in any detail.  If you do, 
please post a usbmon trace of a failed playback.

Alan Stern

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