DSP setup

I've been researching how to get DSP working to support video playback
in my own build system. I'm using kernel 3.2.23's DSP staging drivers
and Buildroot 2012.05's gst and DSP user space support. Based on
reading all I could find about DSP on elinux.org, and specifically
following the DSP Howto an gst-dsp pages on elinux.org, it seems this
may be sufficient though I don't have it working yet.

I put my notes on elinux.org: http://elinux.org/BeagleBox_DSP

Looking this over it seems at least one error shows missing audio
support. Would that keep the video from playing at all? Can I play the
video via gst from X or do I have to play it with X disabled?

Also, I get "iommu fault" listed in /proc/interrupts. Is this an error
and, if so, is there a way to reset this?