ATI HDA - SIGMATEL STAC 9200 CHIPSET How To

From this Fedora forum thread.
Ubuntu launchpad also refers to it where a poster writes that he has finally got his sound to work

He writes: "I have the NVidia MCP51 High Definition Audio with the Sigmatel STAC 9200 chip on it. It came with my Gateway MT3421 laptop."

Here's the instructions:
1. uninstall every alsa package if you have any
rpm -qa | grep -i alsa - if it shows nothing skip this step
and then
rpm -evv --nodeps alsa-... for every package

2. go to www.alsa-project.org and download these files :
alsa-driver-1.0.15rc1.tar.bz2
alsa-lib-1.0.15rc1.tar.bz2
.alsa-utils-1.0.15rc1.tar.bz2

Open a terminal and type : su then make a directory called alsa into /usr/local/src. Copy the files to this directory and unpack them (tar xjvf alsa-... for every file).

3. go to this page and download the file patch_sigmatel.c.patch-1.0.15rc1-simple. Copy the patch to /usr/local/src/alsa.

4. type this :
patch alsa-driver-1.0.15rc1/alsa-kernel/pci/hda/patch_sigmatel.c < patch_sigmatel.c.patch-1.0.15rc1-simple.

5. do this:
cd alsa-lib-1.0.15rc1/
./configure && make && make install
cd ../alsa-utils-1.0.15rc1/
./configure && make && make install
cd ../alsa-driver-1.0.15rc1/
./configure && make && make install

If the configure script complains about missing some libraries yum for them and try again.

6. reboot
7. after rebooting volume may be muted so use kmix or some other mixer to enable it.

Hope it works for you. I have a Gateway MT 3705 laptop and i finally have sound after months of silence

NOTE - on Ubuntu with step 1 you just have to remove alsa-lib and alsa-utils.