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Why no any IMX series supporting PDM Microphone?

Question asked by Kobe Bryant on Oct 4, 2018
Latest reply on Oct 4, 2018 by igorpadykov

My target Platform is IMX7 and IMXRT1050, both adapted Buildroot, it works very well but audio function is always failed using PDM microphone, it seems very strange when I search no any post or project, it's a good cost down way but why no anyone to do it?


I adapted simple-audio-card driver as following setting:


    sound {
        compatible = "simple-audio-card";
        simple-audio-card,name = "OnboardIM69D130";
        simple-audio-card,format = "pdm";
        simple-audio-card,bitclock-master = <&cpu_dai>;
        simple-audio-card,frame-master = <&cpu_dai>;
        simple-audio-card,widgets =
            "Microphone", "Mic Jack";
        simple-audio-card,routing =
            "MIC_IN", "Mic Jack";


        cpu_dai: simple-audio-card,cpu {
            sound-dai = <&sai1>;
            system-clock-frequency = <2400000>;
            dai-tdm-slot-num = <1>;
            dai-tdm-slot-width = <16>;


        simple-audio-card,codec {
            sound-dai = <&dummy_codec>;



and dmesg has no error but also no generate any ALSA devices, please someone can give me directions, thanks!