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

[rpk]

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>;
            };
        };

    };

[ftoliveira]

Hi,

Have you managed to solve your problem?

[yipingwang]

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

[rpk]

Hello,

Attached is a connection diagram of our board.

Regards

Rolf

[yipingwang]

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.