Re: [alsa-devel] Multiple codecs on one sound card for multi-channel sound card

10 Sep 2015


      Hi Mark Brown,
    Looking back on my email notes, you helped me with this back in 2011
with an old kernel version.  I wonder if mutlti-codec-on-single-DAI
configuration is still unsupported by the ASOC core.  I don't see anything
obvious.
If I were to implement it 'properly', what's the right DTS format to go
with?  Something like what I suggest below (i.e. in the simple-audio-card
section, use multiple codecs in a single sound-dai?  If so, where should
the tdm-slot & clocking information go?  In the codec DTS section itself,
or in the sound-dai section?
Thanks again,
 -Caleb
On Tue, Sep 8, 2015 at 6:02 PM, Caleb Crome caleb@crome.org wrote:
...
Hi all,
   What's the current best practices to specify multiple codecs on one
sound card, with all codecs sharing a single TDM bus?
I have a card with up to 32 TLV320AIC33 codecs on it.  For the moment, we
can limit the discussion to only 16 codecs, so we don't have to get extra
serializers involved...
I currently have something like this in my am335x-boneblack.dts file:
(i.e. attempting to set tdm slot width and num in the i2c codec)
but it doesn't seem to be pickin up the fact that I want all the codecs
linked together as one.
(FYI, the first codec, i.e. tlv32aic3x_a should be the master, and all
others including the CPU will be slaves).
Thanks for any help!
BTW, I'm happy to use whatever kernel will support me with the minimal
amount of effort!
Sincerely,
  -Caleb
&i2c1 {
clock-frequency = <100000>;
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&i2c1_pins_default>;
status="okay";
tlv320aic3x_a: tlv320aic3x@18 {
       #sound-dai-cells = <0>;
compatible = "ti,tlv320aic3x";
reg = <0x18>;
status = "okay";
dai-tdm-slot-width = <16>;
dai-tdm-slot-num   = <0>;
};
tlv320aic3x_b: tlv320aic3x@19 {
       #sound-dai-cells = <0>;
compatible = "ti,tlv320aic3x";
reg = <0x19>;
status = "okay";
dai-tdm-slot-width = <16>;
dai-tdm-slot-num   = <2>;
};
tlv320aic3x_c: tlv320aic3x@1a {
compatible = "ti,tlv320aic3x";
reg = <0x1a>;
status = "okay";
dai-tdm-slot-width = <16>;
dai-tdm-slot-num   = <4>;
};
tlv320aic3x_d: tlv320aic3x@1b {
compatible = "ti,tlv320aic3x";
reg = <0x1b>;
status = "okay";
dai-tdm-slot-width = <16>;
dai-tdm-slot-num   = <6>;
};
};
sound {
     compatible = "simple-audio-card";
     simple-audio-card,name = "puck audio";
     // simple-audio-card,widgets=
     // simple-audio-card,routing=
     simple-audio-card,mclk-fs = <256>;
     status="okay";
     simple-audio-card,bitclock-master = <&tlv320aic3x_a>;
     simple-audio-card,frame-master    = <&tlv320aic3x_a>;
     simple-audio-card,dai-link@0 {
          format = "left_j";
  cpu {
    sound-dai = <&mcasp0 0>;
  };
// *** Here's where I'm really confused -- this part doesn't seem to be
supported to
// have all the codecs on a single DAI.
// The examples given  seem to be for different codec DAIs
// sharing a single CPU DAI, but not used at the same time.
codec {
    #sound-dai-cells = <0>;
    sound-dai          = <
    &tlv320aic3x_a
    &tlv320aic3x_b
    &tlv320aic3x_c
      &tlv320aic3x_d
    >;
  };
     };
};