Bug#537600: pulseaudio: Underrun on 'ALSA Playback', 0 bytes in queue.

[Daniel Chen]

It looks like resolving this symptom requires application of these
changesets from upstream git (I've omitted the authors below, but
they're easily referenced):

commit 70dded6aba653b5f70b48fda22f9b322fd3ae2c9
Author: Clemens Ladisch <clemens at ladisch.de>
Date:   Mon Nov 15 10:33:35 2010 +0100

    pcm: pass hw_params flags to slave


commit 7c99bd24bcf6852d55e90e0f42f7ac5ea8f14fbb
Author: Clemens Ladisch <clemens at ladisch.de>
Date:   Mon Nov 15 10:43:13 2010 +0100

    support for period wakeup disabling

    Add API to disable period wakeups.


commit ba9332e9192814a5431a3a2505d25d74a9232124
Author: Jaroslav Kysela <perex at perex.cz>
Date:   Thu Nov 18 09:27:07 2010 +0100

    pcm: fix snd_pcm_avail_delay() function


commit aba87e509898ec9ddb3e319267d7c267409ff100
Author: Pierre-Louis Bossart <pierre-louis.bossart at intel.com>
Date:   Tue Nov 23 08:47:08 2010 -0600

    pcm_plugin: fix delay