ALSA, CMI8330, and devfs

[Shawn]

Hi everyone. After gleaning bits of information here and elsewhere on the net I've come up with this solution for the CMI8330 under ALSA. So far most apps seem happy in their default operation.

Place these lines in /etc/devfsd.conf. (I placed mine at the end of the ALSA/OSS section.)

REGISTER snd/pcmC0D1p CFUNCTION GLOBAL mksymlink pcmC0D1p snd/pcmC0D0p
REGISTER sound/dsp CFUNCTION GLOBAL unlink dsp
REGISTER sound/dsp CFUNCTION GLOBAL mksymlink sound/adsp dsp


Then do (or reboot):
/etc/init.d/alsasound stop
killall -USR1 devfsd
/etc/init.d/alsasound start

The values above would differ if you have additional cards.

Regards,
Shawn

[TheCoop]

what exactly does this do/solve?
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[Shawn]

Greetings Coop,

Guess the post was a little incomplete, wasn't it? <g>

After emerging/configuring ALSA...
(This is somewhat paraphrased, the /dev references are correct.)

aplay complained:
"Can't open /dev/pcmC0D0p. No such device."

play complained:
"Can't open /dev/dsp. No such device."

xmms comlained:
"Can't open device... Are you sure you ..."

The problem seems to be in the way the CMI8330 and/or the driver handles full-duplexing. After installation the device(s) mapping apparently is:

/dev/dsp -> /dev/sound/dsp == pcmC0D0c (the wss half as recorder?)
/dev/sound/adsp == pcmC0D1p (the sb16 half as playback?)

It seemed that play (and other OSS apps) were not happy because /dev/dsp is not a playback device and aplay was not happy because /dev/snd/pcmC0D0p didn't even exist.

The lines added to the /etc/devfsd.conf file either create or change the symlinks so that the app's default expectations are met. At least that is my theory so far. <g> I'm new to Gentoo and am certainly not a world expert on Linux. Comments welcome.

-Shawn