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

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

950 Views
rpk
Contributor II

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>;
            };
        };

    };

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4 Replies

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ftoliveira
Contributor I

Hi,

Have you managed to solve your problem?

 

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720 Views
yipingwang
NXP TechSupport
NXP TechSupport

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

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rpk
Contributor II

Capture.PNG

Hello,

Attached is a connection diagram of our board.

Regards

Rolf

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720 Views
yipingwang
NXP TechSupport
NXP TechSupport

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) cant 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.

 

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