[Realtek ALC887-VD] Playback only through 2 channels by default

[Dan Watkins]

Ubuntu does not detect my 5.1 surround sound[0] by default. In order to get it detected, I have to do the following:

1) Open alsamixer
2) Change the "Channel Mode" setting from "2ch" to "6ch" (there is also a "4ch" setting)
3) `pulseaudio -k`

I have to do this on every boot, as the "6ch" setting is not remembered.

[0] My soundcard and sound system are 5.1, but I actually only have front left, center, right and the subwoofer. This shouldn't affect how Ubuntu acts at all (because it can't know what speakers I have plugged in to my subwoofer), but will mean that I can't report on whether or not rear channels are working as expected.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: alsa-base 1.0.25+dfsg-0ubuntu4
ProcVersionSignature: Ubuntu 3.19.0-30.34-generic 3.19.8-ckt6
Uname: Linux 3.19.0-30-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: daniel 24007 F.... pulseaudio
CurrentDesktop: Unity
Date: Tue Oct 13 10:23:16 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-07-30 (439 days ago)
InstallationMedia: Ubuntu-Server 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.3)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:PCH successful
Symptom_Card: Built-in Audio - HDA Intel PCH
Symptom_Jack: Green Line Out, Rear
Symptom_PulsePlaybackTest: PulseAudio playback test successful
Symptom_Type: Only some of outputs are working
Title: [MS-7788, Realtek ALC887-VD, Green Line Out, Rear] Playback problem
UpgradeStatus: Upgraded to vivid on 2015-08-24 (49 days ago)
dmi.bios.date: 01/18/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V2.3
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: H61M-P31 (G3) (MS-7788)
dmi.board.vendor: MSI
dmi.board.version: 1.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV2.3:bd01/18/2012:svnMSI:pnMS-7788:pvr1.0:rvnMSI:rnH61M-P31(G3)(MS-7788):rvr1.0:cvnMSI:ct3:cvr1.0:
dmi.product.name: MS-7788
dmi.product.version: 1.0
dmi.sys.vendor: MSI
modified.conffile..etc.modprobe.d.alsa.base.conf: [modified]
mtime.conffile..etc.modprobe.d.alsa.base.conf: 2015-08-05T11:15:16.899686

[Raymond (superquad-vortex2)]

control.1 {
  iface MIXER
  name 'Channel Mode'
  value '2ch'
  comment {
   access 'read write'
   type ENUMERATED
   count 1
   item.0 '2ch'
   item.1 '4ch'
   item.2 '6ch'
  }
 }

this channel mode control limit the availability of 5.1 since the two input jacks have to retask as output jacks

you need to discuss this issue in alsa-devel mailing list and pulseaudio-discuss mailing list

possible way is to add hook which change channel mode when using surround40, surround51

http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/conf/cards/HDA-Intel.conf;hb=HEAD

similar to

http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/conf/cards/ICH4.conf;hb=HEAD

[Raymond (superquad-vortex2)]

hooks.0 {
                        type ctl_elems
                        hook_args [
                      {
                               name "Channel Mode"
                               preserve true
                               value "6ch"
                                 lock true
                                 optional true
                       }
}

[Raymond (superquad-vortex2)]

you need to add hook to front device and surround40 in order to get back the input jacks after probing surround51

hooks.0 {
   type ctl_elems
   hook_args [
   {
    name "Channel Mode"
    preserve true
    value "2ch"
    lock true
    optional true
   }
}

hooks.0 {
   type ctl_elems
   hook_args [
   {
    name "Channel Mode"
    preserve true
    value "4ch"
    lock true
    optional true
   }

[Raymond (superquad-vortex2)]

http://www.intel.com/support/motherboards/desktop/sb/CS-034198.htm

Audio jack retasking is a feature that allows a jack to support more than one function. For example, the pink audio jack can support microphone input when the system configuration is set to stereo mode, 2-channel, and as Center/LFE or Rear Surround, when set to 6-channel mode.

[Launchpad Janitor (janitor)]

[Expired for alsa-driver (Ubuntu) because there has been no activity for 60 days.]