LayerscapeのトピックRe: Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

rpk — Fri, 28 Feb 2020 07:41:59 GMT

Hello,

I am working on bringup of a custom board with a LS1028A and three ADAU1761 codecs. The codecs are supposed to be configured in TDM8 mode and share a common playback I2S bus connected to SAI4, and a common capture I2S bus connected to SAI3.
What is the recommended way of modelling this setup in the Linux device tree ?

So far I have tried the following:

&i2c0 {
    status = "okay";

   i2c_codec1: adau1761@38 {
       compatible = "adi,adau1761";
       #sound-dai-cells=<0>;
       reg = <0x38>;
       tdm-offset = <0>;
       clocks = <&adau1761_mclk>;
       clock-names = "mclk";
   };

   i2c_codec2: adau1761@39 {
       compatible = "adi,adau1761";
       #sound-dai-cells=<0>;
       reg = <0x39>;
       tdm-offset = <16>;
       clocks = <&adau1761_mclk>;
       clock-names = "mclk";
   };

   i2c_codec3: adau1761@3a {
       compatible = "adi,adau1761";
       #sound-dai-cells=<0>;
       reg = <0x3a>;
       tdm-offset = <32>;
       clocks = <&adau1761_mclk>;
       clock-names = "mclk";
   };
};

At first I attempted creating three simple-audio-card's. That attempted failed since sharing the same cpu (SAI3 and SAI4) failed with no ALSA device as a result.

Then I attempted cerating a single simple-audio-card with a dai-link containing two cpu sub-nodes and three codec sub-nodes. ALSA enumerates this device, and I get the expected ADAU1761 controls for a single codec. But how do I get the two other sets of ADAU1761 controls? And how do I do the widgets and routing for this ?

Note: The widgets and routing below is just experimental.

sound {
       status = "okay";
       compatible = "simple-audio-card";
       simple-audio-card,format = "i2s";

        simple-audio-card,widgets =
           "Headphone", "O1 Headphone",
           "Headphone", "O2 Headphone",
           "Headphone", "O3 Headphone";

        simple-audio-card,routing =
           "Playback", "O1 Headphone",
           "Playback", "O2 Headphone",
           "Playback", "O3 Headphone";

       simple-audio-card,dai-link {
           format = "i2s";
           convert-channels = <8>;
           bitclock-master = <&snd_dai_playback>;
           frame-master = <&snd_dai_playback>;

           snd_dai_capture: cpu@0 {
               sound-dai = <&sai3>;
               dai-tdm-slot-num = <8>;
               dai-tdm-slot-width = <16>;
           };

           snd_dai_playback: cpu@1 {
               sound-dai = <&sai4>;
               dai-tdm-slot-num = <8>;
               dai-tdm-slot-width = <16>;
           };

           codec@0 {
               sound-dai = <&i2c_codec1>;
               frame-master;
               bitclock-master;
               system-clock-frequency = <25000000>;
           };
           codec@1 {
               sound-dai = <&i2c_codec2>;
               system-clock-frequency = <25000000>;
           };
           codec@2 {
               sound-dai = <&i2c_codec3>;
               system-clock-frequency = <25000000>;
           };
       };

};

Re: Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

yipingwang — Mon, 16 Mar 2020 05:10:08 GMT

Can you please share the block diagram or connection diagram of your board, which can show the audio data flow between source and sink.

Re: Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

rpk — Fri, 20 Mar 2020 08:16:56 GMT

Hello,

Attached is a connection diagram of our board.

Regards

Rolf

Re: Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

yipingwang — Wed, 25 Mar 2020 02:27:50 GMT

We don't have a such set up with multiple codecs, so we can suggest you some experiments to work with -

1) As per our understanding either SAI or codec can be the master device for bit clock and frame clock.

So if codec@0 is set as master then SAI (cpu) can’t be set as master it should be slave device.

codec@0 {

sound-dai = <&i2c_codec1>;

frame-master;

bitclock-master;

system-clock-frequency = <25000000>;

};

bitclock-master = <&snd_dai_playback>;

frame-master = <&snd_dai_playback>;

Your block diagram depicts U54 Codec #3 as the master, so make sure you populate these values correctly.

2) Can you also try with multiple dai-link nodes, one for each codec I am referring to Documentation/devicetree/bindings/sound/simple-card.txt, Example #2, where both dai-link@1 and dai-link@2 have same cpu subnode but different codec node.

Re: Linux ALSA device tree bindings for 3 codecs connected to 2 x SAI on LS1028A

ftoliveira — Tue, 30 Mar 2021 12:14:53 GMT

Hi,

Have you managed to solve your problem?