Description of problem:
Certain sound cards when configured in surround sound mode produce garbled sound when used with PulseAudio and ALSA PulseAudio plugin.

Version-Release number of selected component (if applicable):
alsa-plugins-pulseaudio 1.0.21

How reproducible:
Always

Steps to Reproduce:
1. Use card driven by snd-ca0106 driver
2. Configure sound card to work in 4.0, 5.1 or 7.1 mode
3. "aplay -B 100000 <Sound.wav>"
  
Actual results:
Sound is mangled beyond recognition; both aplay and pulseaudio report high number of underruns.

Expected results:
Song played properly.

Additional info:
Updating to alsa-plugins-pulseaudio 1.0.24 or simply back-porting following commit fixes the problem:

commit c20d516e229620129ee20175d8fee8511cc3a4bd
Author: Takashi Iwai <tiwai>
Date:   Fri Jul 9 14:05:03 2010 +0200

    pulse: Add handle_underrun option
    
    Added a config option "handle_underrun" to specify whether pulse plugin
    handles the underrun reported from PA.  The default value is now set to
    false, i.e. it will ignore underruns in PA (for good reasons below).
    You can take back to the old behavior by setting handle_underrun true.
    
    The original idea was brought by David Henningsson <diwic>,
    while this patch is simplified and makes the behavior configurable.
    
    The reasons for avoiding underruns (cited from David's original patch):
    
     Reporting underruns to ALSA seems to do more bad than good, for these reasons:
     * If pulseaudio gets an underrun, the normal way to end that underrun is to
       feed it with more buffers. This is different from the ALSA way of dealing
       with underruns, which requires hardware buffer pointers to be reset.
     * In addition, underrun signals are delivered asynchronously from pulseaudio.
       This means that there might be more buffers on the way to pulseaudio when
       the underrun is reported, making the underrun obsolete. Unfortunately,
       there is currently no known way to determine whether this is the case or
       not.
    
    Signed-off-by: Takashi Iwai <tiwai>