* add a callback for initialising the mixer interface
* support ac97 2.1 variable rate audio feature
fix ac97-using drivers for the above
add suspend/resume support for neomagic
then invoke the children. As the value of HISR can be read
only once, pass the HISR to the children via struct
csa_bridgeinfo, stored in the ivars of them.
- Clear the contents of serial FIFO upon stopping the DMA for
playing. This may eliminate buzz on playing. Experimental.
Also, optimize out a mess of #if's that were duplicating work already
done by config(8). For example, if a file is marked as
"dev/sound/pci/foo.c optional pcm pci" then it's only added if pcm *and*
pci are present, so #if NPCM > 0 and #if NPCI > 0 are totally redundant.
A bit more work is still needed.
Discussed with: cg (a few weeks ago)