[alsa-devel] Need general idea how to architect driver for multi-codec board

Caleb Crome caleb at crome.org
Thu Jun 2 00:17:10 CEST 2011

Hi Again,
  Sorry to keep on this, but I'm really wedged.  I can't tell if I'm trying
to break new ground, or if I just don't know what I'm doing :-)  Or both

I've got my multi-codec card instantiating (only 4 codecs here for
simplicity -- there are really 8 total)

# insmod tlv320aic3x_se.ko   # <--- my custom version of aic3x driver.
# insmod puppy_machine.ko  # <-- my custom machinne interface with all my
dai-links and all.

# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: tlv320aic33se [tlv320aic33-se], device 0: tlv320aic33-se
tlv320aic3x-se-hifi-0 []
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 0: tlv320aic33se [tlv320aic33-se], device 1: tlv320aic33-se
tlv320aic3x-se-hifi-1 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: tlv320aic33se [tlv320aic33-se], device 2: tlv320aic33-se
tlv320aic3x-se-hifi-2 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: tlv320aic33se [tlv320aic33-se], device 3: tlv320aic33-se
tlv320aic3x-se-hifi-3 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

I can run jack on the first subdevice and it actually streams data both ways
on codec 0.

# jackd -d alsa -d hw:0,0
creating alsa driver ...
control device hw:0

However, I can't seem to get access to any of the other codecs on the TDM
bus.  Remember, there is only a single CPU DAI here (a single McBSP port),
but multiple codec DAIs (one for each codec, in TDM mode).

# jackd -d alsa -d hw:0,0 -i4 -o4   # <--- Does not work.  hw:0,0 is just a
single stereo codec, so it doesn't start up the other DAIs

How do I get jackd (or anything else for that matter), to start all the DAIs
at the same time?

If I try:
# aplay -D hw:0,0 -f S16_LE test.wav    # <--- success

and in another shell:
# aplay -D hw:0,1 -f S16_LE test1.wav  # <--- failure

the second invocation on hw:0,1 fails because hw:0 is already open.

I also tried modifying my asoundrc to something similar to
http://quicktoots.linuxaudio.org/toots/el-cheapo, but that didn't work

I can attach my code and even schematic if that would help.

Thanks again,

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