• Audio Problems or Issues

VIA 8237 Sound Problem in Linux

Submitted by mhulboj on Sat, 2006-02-04 11:42. Technical

I had problems with sound under Kubuntu Breezy Badger (5.10) running originally packaged kernel (2.6.12-10) and ALSA (1.0.9b-4). The computer is equipped with an MSI motherboard (KM4M-V or something really similar). Sound is provided by an integrated VT8237 chipset and the responsible module is called via82xx.

So what was the problem and what steps were necessary to get rid of it? The initial problem was that trying to play any sound yielded no result. For most of the next steps I have been using following command to test whether the sound is somehow working:

cat /dev/urandom > /dev/dsp

First thing was to check if sound is working at all on this machine. It was tested under Windows XP and indeed it is possible to get the sound working (without problems).

Next I had checked whether the channels are not muted. By default all ALSA channels come muted - and sometimes it may cause some confusion. Yet it turned out that all the needed channels were unmuted (use alsamixer for this).

After that I had looked at the dmesg output to see if there were any strange messages related to via82xx. I found something:

[4294696.737000]           via82xx: Assuming DXS channels with 48k fixed sample rate.

[4294696.737000]          Please try dxs_support=5 option

[4294696.737000]          and report if it works on your machine.

[4294696.737000]          For more details, read ALSA-Configuration.txt.

I have checked that there are few possible options for dxs_support variable. I have tried them out and seen no change. In the end I have left following option:

options snd_via82xx dxs_support=4

I have looked at various results returned by Google, but haven't found anything particularly interesting (a lot of various problems but none seem to be related with mine). I still didn't have enough information to utilise Google knowledge properly.

I have played a bit with alsactl tool and finally discovered something strange. I have issued following commands:

root@jc:/home/mhulboj# alsactl power 0 off

Power state for card #0 is D3hot

root@jc:/home/mhulboj# alsactl power 0 on

Power state for card #0 is D0

root@jc:/home/mhulboj# cat /dev/urandom > /dev/dsp

And after that I was able to hear the noise for about five seconds. After that time everything was dead as previously. If I issued above commands again - it would again work for few seconds.

This last discovery was very interesting and when compared against Google search results it turned out that few people had similar problem. After some more searching I have found a solution - one needs a custom .asoundrc (or global /etc/asound.conf) file. The contents of the file should be (works for me):

pcm.dmixer {

    type dmix

        ipc_key 1024

    slave {

            pcm "hw:0,0"

            period_time 0

            period_size 1024

            buffer_size 8192

       rate 44100

           }

       bindings {

               0 0

               1 1

           }

   }

   pcm.dsp0 {

       type plug

           slave.pcm "dmixer"

   }

   pcm.!default {

           type plug

           slave.pcm "dmixer"

   }

   pcm.default {

      type plug

         slave.pcm "dmixer"

   }

 ctl.mixer0 {

     type hw

         card 0

   }