[Lancaster] onboard sound - cmedia 9738

[Andy Baxter]

just finally got the onboard sound working on my new motherboard. This is 
mainly meant for Richard Robinson, because I think he has a similar sound 
chip, but I posted it to the list in case anyone else has onboard ac'97 
sound.

The chip is a cmedia 9738, driven by a SIS 7012 AC'97 controller. The problem 
is, the OSS driver supplied by CMedia doesn't work properly - xmms plays 
scratchy sound; some apps don't work at all.

Eventually I found out that the Ac'97 interface is standardised enough that I 
could use the intel8x0 ac'97 driver that's comes with alsa (Advanced Linux 
Sound Archictecture). This will also drive the SIS 7012 controller.

To get it working, what I did was:

installed the alsa library and utilities (but not the drivers) from debian 
using apt-get.
recompiled the kernel with raw sound support only (as a module - soundcore.o) 
- no OSS driver, no card drivers.
downloaded, compiled, and installed the alsa drivers source.
put snd, snd-intel8x0, and snd-pcm-oss in /etc/modules. (The latter gives OSS 
emulation for older applications).

a small gotcha is that alsa sets all mixer controls to zero volume, muted, on 
start up, so you need to set these right before you can hear the output. Once 
I did this, the /etc/init.d script for alsa that debian installed seems to be 
taking care of preserving the mixer settings between shutdown and boot-up.

andy.