[Debian-eeepc-devel] Sound problem solved on the EeePC 900, kernel 2.6.25

[Neil Hoggarth]

Just a brief follow-up to the recent messages from Niccolo Rigacci and 
Davide Cavalca. I'm also pleased to say that I am happily using a 
DebianEeePC installation on my new EeePC 900 - my thanks to all the 
developers and contributors who have made this possible!

Lack of working sound with the 2.6.24 kernel was a big issue for me (one 
of the main things that I want to use my 900 for is as a portable media 
player).

I downloaded a linux-2.6.25.4 tarball from kernel.org, made oldconfig 
using the config from the DebianEeePC 2.6.24 kernel as a basis, and used 
kernel-package to build a deb. Then I used eeepc-acpi-source and 
atl2-source in conjunction with module-assistant to build modules.

The resulting kernel and modules work well enough for my purposes, though 
I get the impression that there are still some unresolved issues in the 
interaction between the sound hardware, the snd-hda-intel driver and ACPI. 
Specifically:

The machine does not correctly power off after shutdown, unless the 
snd-hda-intel driver is removed first (this can be worked around by 
putting an S script to rmmod the driver in /etc/rc0.d/).

The sound doesn't work when the system resumes after suspend - in this 
situation it behaves much like the sound in the 2.6.24 kernel, the module 
is loaded, the devices exist in /dev and can be opened by programs, but 
nothing is heard when one tries to play sound. This can be worked around 
by manually removing and reloading the the snd-hda-intel module after a 
resume.

I have just started playing with PowerTOP, and I notice that the system 
uses the C3 state until the sound device is used. Once sound has been used 
(however briefly) it never goes below C2. Again, rmmod/modprobe on 
snd-hda-intel "fixes" things and the system starts going into C3 again 
(until the next sound is played).

Regards,

Neil.