Multichannel problems with snd_hda_intel

[Guinpen]

Hello everyone,

I have the following audio device:

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00:0f.1 Audio device: nVidia Corporation MCP55 High Definition Audio (rev a2)
        Subsystem: nVidia Corporation Unknown device c55e
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 316
        Memory at cfff0000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: [44] Power Management version 2
        Capabilities: [50] Message Signalled Interrupts: Mask+ 64bit+ Queue=0/0 Enable+
        Capabilities: [6c] HyperTransport: MSI Mapping

It came with an Evga NF680i board, has an ALC882/885 chip, and works with the snd_hda_intel driver. I have gentoo-sources 2.6.20-r3 kernel with in-kernel ALSA modules (1.0.14_rc1) on an AMD64 system.

Problem 1: With no .asoundrc in place, stereo input plays over all 8 channels. Why does it do that without my asking for it? I can control each channel just fine in alsamixer.

Problem 2: Any attempt to play anything over a non-default ALSA device hangs the corresponding program. I tried:

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aplay -D front Surround-SDL-testfiles/chan-id.wav
aplay -D surround51 Surround-SDL-testfiles/chan-id.wav
aplay -D plug:surround51 Surround-SDL-testfiles/chan-id.wav
speaker-test -D surround51 -c 6 -t wav
...

All these hang. Note that this one doesn't (but gives an error):

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play -D plughw:surround51 Surround-SDL-testfiles/chan-id.wav
ALSA lib pcm_hw.c:1357:(_snd_pcm_hw_open) Invalid value for card
aplay: main:545: audio open error: No such device

Here's some more information:

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aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: ALC882 Analog [ALC882 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 1: ALC882 Digital [ALC882 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

aplay -L
default:CARD=NVidia
    HDA NVidia, ALC882 Analog
    Default Audio Device
front:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    Front speakers
surround40:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=NVidia,DEV=0
    HDA NVidia, ALC882 Digital
    IEC958 (S/PDIF) Digital Audio Output
null
    Discard all samples (playback) or generate zero samples (capture)

Nothing unusual appears in my kernel log. Here's /etc/modules.d/alsa:

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alias char-major-116 snd
alias char-major-14 soundcore

alias snd-card-0 snd-hda-intel
alias sound-slot-0 snd-card-0

alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss

alias /dev/mixer snd-mixer-oss
alias /dev/dsp snd-pcm-oss
alias /dev/midi snd-seq-oss

options snd cards_limit=1

options snd_hda_intel model=6stack-dig
options snd_hda_intel enable_msi=1

The model parameter helps to set my alsamixer controls correctly, as the module is unable to detect them properly by itself, and otherwise swaps the side and rear channels. It makes no other difference to the two problems above. The second parameter seems to have no effect, although lspci claims it should work and I read it improves performance.

Thank you in advance for any advice.

[djscribble]

Did you ever get this fixed?? (i am noticing the same issue with 2.6.21-gentoo-r4) Also, what did you put in your .asoundrc to fix this??

thanks!

[Guinpen]

No, I haven't fixed this.

[Guinpen]

OK, it seems that 2.6.23 works better. Now a 6 channel WAV will play correctly over each channel! However, I still can' t solve problem 1: why does stereo replicate over all channels?

I'm also a little confused over ALSA's separation between devices and device plugins. Take "surround71" or "front":

1. Are these devices (that eventually map to the same sound card), or are they plugins of the hw0:0 device?
2. What is the hw0:0 device in terms of channels?
3. What is the default device?
4. Why does surround71 not have dmix?

Thanks for any information. Does anyone have a 7.1 test file by the way?