[alsa-devel] Configure and use dmix with a new ASoC driver

[Simon Tremblay]

Hi, 

I don't know if there is something special I should do to be able to use dmix
with my new ASoC driver I made (TLV320AIC23b codec running on a AT91RM9200
 board).

The problem is when I try to use dmix with aplay, it doesn't work and I got
 this error message:

# aplay -v -D plug:dmix /media/usb0/tada.wav
aplay: main:545: audio open error: Operation not permitted
#

Listing of my /dev/snd:

# ls -al /dev/snd
drwxr-xr-x    2 root     root            0 Jan  1 00:01 .
drwxr-xr-x    7 root     root            0 Jan  1 00:01 ..
crw-rw----    1 root     audio    116,   0 Jan  1 00:01 controlC0
crw-rw----    1 root     audio    116,  16 Jan  1 00:01 pcmC0D0p


Notice I have a default /usr/share/alsa/alsa.conf file too. I'm running ALSA
1.0.15. Of course, it works well when I play a sound without the -D plug:dmix
parameter...

# aplay /media/usb0/tada.wav
at91-ssc:ssc_startup: SSC_SR=0x000004c3
armus_tlv320aic23b: pck1 started
asoc: aic23b <-> at91-ssc1 info:
asoc: rate mask 0x6fe
asoc: min ch 1 max ch 2
asoc: min rate 8000 max rate 96000
Playing WAVE '/media/usb0/tada.wav' : Signed 16 bit Little Endian, Rate 48000
Hz, Stereo
#

I tried to find some useful documentation about dmix but mainly it says that
when we have a recent version of ALSA, we don't need to configure it because
it's already done?