[gentoo-amd64] problem with multi-channel alsa on hda-intel

[Raffaele BELARDI <raffaele.belardi@st.com>]

Until last world update I was happily using the following .asoundrc [1]
to duplicate stereo sound from front to rear channels (the former is
connected to a 2.1 system, the latter to a hi-fi equipment):

pcm.ch40dup {
 type route
 slave.pcm surround40
 slave.channels 4
 ttable.0.0 1
 ttable.1.1 1
 ttable.0.2 1
 ttable.1.3 1
 }

and then "mplayer -channels 4 -ao alsa:device=ch40dup" gave me the
duplicated stereo sound on 4 channels.

After last update alsa-lib went from 1.0.19 to 1.0.20 and kernel 2.6.29
to 2.6.30 and mplayer sound stopped working from any channel with the
following error:

Trying preferred audio driver 'alsa', options 'device=ch40dup'
alsa-init: requested format: 48000 Hz, 2 channels, 9
alsa-init: using ALSA 1.0.20
alsa-init: setup for 1/2 channel(s)
alsa-init: using device ch40dup
alsa-init: pcm opened in blocking mode
[AO_ALSA] Unable to get initial parameters: Invalid argument
Failed to initialize audio driver 'alsa:device=ch40dup'
Could not open/initialize audio device -> no sound.

If I remove the "-ao alsa:device..." bit from the mplayer command line I
get stereo sound from the front speakers only.

This is with HDA-intel driver on Nvidia nForce430/AD1986 chipset, icewm
desktop. I just read from the kernel doc [2] that there is a "model
name" parameter that defaults to '6stack' while my model is '3stack' so
tonight I will try that.

Any other hints before I try upstream?

thanks,

raf

[1]
http://alsa.opensrc.org/index.php/Playing_stereo_on_surround_sound_setup_%28Howto%29

[2] /usr/src/linux/Documentation/sound/alsa/HD-Audio-Models.txt