[alsa-devel] [RFC] ALSA: Reduce delay for a blocking pcm_drain.

[Raymond Yau]

>
> This can be worked around in user space as well by using a nonblocking
drain and
> sleeping based on how many samples are queued.  Would that be the right
thing to
> do or is this (or something similar) worth fixing here.
>
> To test this I opened a pcm and set no period wakeups, played a few
samples and
> then called drain, which hung indefinitely.  Using a USB headset with a
> max period size of 128k but only 15ms of the buffer filled, having the
> drain time shorter without losing samples makes a blocking call
> feasible.
>

Do you mean that you tested on a patched version of USB audio driver since
only three drivers support
SNDRV_PCM_INFO_NO_PERIOD_WAKEUP

http://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/log/sound?qt=grep&q=period+wakeup