I've been looking over the spec for the Realtek ALC885 and comparing it with an earlier patch for the Mac Mini in the Sigmatel code. I'm wondering if Apple is using the same GPIO mute function as on the Mini. Attached is a patch to test that theory. It essentially sets the system up as a 3 stack audio (which may be wrong as it is), but also unmutes the gpio registers.

To test it, start with either the alsa-driver-hg20061130.tar.bz2 or download the recent 1.0.14rc1 and follow these instructions:
tar -jxvf alsa-driver-<version>.tar.bz2 # <version> == hg20061130 or 1.0.14rc1
cd alsa-driver-<version>/alsa-kernel
patch -p1 <macpro.patch.1
cd ..
./configure --with-cards=hda-intel --with-debug=detect ; make ; make install
dmesg -c
modprobe -r snd-hda-intel
modprobe snd-hda-intel model=macpro
dmesg >dmesg.out

Send me a copy of dmesg.out along with any differences that you see. I may need to tweak which pins get enabled.

Tobin

On Thu, 2006-12-07 at 08:44 -0600, Shaw Terwilliger wrote:

Shaw Terwilliger wrote:
>> This is actually good info.  Interesting that sound is coming out from
>> the Surround channels.  The low volume could mean that EAPD still needs
>> to be set.
>>
>> I'll look more into this tomorrow.  Hopefully I can get a patch for you
>> to test.
> 
> Thanks for all your help.  I'm happy to test any patches you come up with.

Have you had a chance too cook up any patches for the Mac Pro HDA
hardware?  I fooled around with different models yesterday, and the
"auto" model detects very few output channels (PCM, Front, Line-in), but
correctly assigns the front channel.  It's still incredibly quiet.

--
Tobin Davis <tdavis@dsl-only.net>