[bug] SPDIF (digital-out) not working on NForce4/CK804

[Gilles Hemberg <gilles.hemberg@gmail.com>]

Hi all,

Sorry to bump in like this, but I was advised to submit a bug-report for 
the ALSA-drivers on my HTPC: no sound comes through out of my AVR when I 
select the digital output through SPDIF (TOSLINK).


The relevant parts of my HTPC are as follows:
     * CPU: Athlon64 X2 3800+
     * Motherboard: ASUS A8N-SLI Deluxe motherboard (BIOS 1805) NForce4 
with CK804 sound (relying on a Realtek ALC850 chip)
     * RAM: 2x 512 MB DDR-400
     * GPU: nVidia Geforce GT240 (which carries a HDMI port and uses the 
snd-
     * Receiver: Marantz SR7500 (supporting both Dolby Digital 5.1 and 
DTS decoding), connected to motherboard's SPDIF TOSLINK port (optical) + 
JBL 5.1 speaker-set
     * OpenElec 4.2.0: Kernel 3.16.3, Alsa 1.0.28


Symptoms:
Speaker-test does not produce any sound. Command used is as follows:

     speaker-test -c2 -r 48000 -D hw:0,2

No sound either from other applications (such as XBMC 13.2).

SPDIF worked flawlessly on the exact same hardware & connections using 
Win7/XBMC.
Sound does come through the SPDIF when I use hw:0,0 (= analog device).


Things tried (none working):
     * Blacklisting snd-hda-intel (= HDMI from my GPU) to make sure 
CK804 is the only sound chip visible.

     * amixer set 'IEC958 Playback AC97-SPSA' Playback 100% unmute

     * Contacted XBMC developer via IRC for investigation: concluded 
that problem would be with kernel driver, advised to create this bug-report.

     * Tried another distro (Ubuntu from XBMCBuntu 13.0).


Further details which might be useful:
     * alsa-info.sh output: http://pastebin.com/Bp2ZGfZb

     * /proc/asound/card0/ac97#0-0: http://pastebin.com/Q5y1J0Ra

     * /proc/asound/card0/ac97#0-0+regs: http://pastebin.com/tBbTCxZg


Similar reports found (no working solution):
http://mailman.alsa-project.org/pipermail/alsa-devel/2009-September/021336.html
http://askubuntu.com/questions/264272/no-sound-output-msi-k8n-neo4-ck804-ac97
http://askubuntu.com/questions/462605/new-install-of-ubuntu-14-04-trusty-3-audio-devices-no-sound
     https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=615225
     http://ehc.ac/p/alsa/mailman/message/25973743/
     http://wiki.linuxmce.org/index.php/ASUS_A8N-SLI_Deluxe
     http://forum.xbmc.org/showthread.php?tid=156043&pid=1348176
     http://forum.xbmc.org/showthread.php?tid=168608
     http://ubuntuforums.org/showthread.php?t=2210288
     http://cholla.mmto.org/computers/linux/sound/asus_a8ne.html
     http://www.nvnews.net/vbulletin/showthread.php?t=80521
     ...


I am willing to test or provide further details where needed. I am new 
to Linux, but am a developer myself (C#) so I know how to look up some 
info... Hoping I haven't offended any of you with this post.

THNX,
Bye!