View source for Pillgram::Audio

= TLV320AIC3110 =
== Schematics ==
[[File:Tlv320aic3110-schematics-copyright.png|thumb]]

== Device Tree ==
<syntaxhighlight>
/dts-v1/;
/plugin/;
  
/ {
    compatible = "brcm,bcm2712", "brcm,bcm2711", "brcm,bcm2835";
    // compatible = "brcm,bcm2835";
 
    fragment@0 {
        target = <&i2s_clk_consumer>;
        __overlay__ {
            status = "okay";
            #sound-dai-cells = <0>;
            brcm,tx-channels = <2>;
            brcm,rx-channels = <1>;
        };
    };
 
    fragment@1 {
        target-path = "/";
        __overlay__ {
            status = "okay";
 
            codec_1v8_reg: codec-1v8-reg {
                compatible = "regulator-fixed";
                regulator-name = "tlv320aic3104_1v8";
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
                regulator-always-on;
                status = "okay";
            };
        };
    };
 
    fragment@2 {
        target = <&i2c1>;
        __overlay__ {
            #address-cells = <1>; /* Single cell for I2C address */
            #size-cells = <0>;    /* No size cells for I2C devices */
            status = "okay";
 
            tlv320aic3110: tlv320aic3110@18 {
                compatible = "ti-pg,tlv320aic3110", "ti,tlv320aic3110", "ti,tlv320aic311x"; 
                reg = <0x18>;
                #sound-dai-cells = <0>;
                // system-clock-frequency = <12288000>;  // Codec clock config
                // system-clock-direction-out;           // Codec as master
                status = "okay";
 
                HPVDD-supply = <&vdd_3v3_reg>;
                SPRVDD-supply = <&vdd_5v0_reg>;
                SPLVDD-supply = <&vdd_5v0_reg>;
                AVDD-supply = <&vdd_3v3_reg>;
                IOVDD-supply = <&vdd_3v3_reg>;
                DVDD-supply = <&codec_1v8_reg>;
 
                clocks = <&mclk_external>;
                clock-names = "mclk";
                // system-clk-frequency = <12288000>;
                mclk-frequency = <12288000>;
                // gpio-controller;
 
                reset-gpios = <&gpio 13 1>; // GPIO 13 as active low reset
                reset-delay-us = <10000>;     /* 10ms delay */
 
                // Debug properties (must precede subnodes)
                debug;
                linux,debug;
 
            };
        };
    };
 
    fragment@3 {
        target = <&sound>;
        __overlay__ {
            compatible = "simple-audio-card";
            i2s-controller = <&i2s_clk_consumer>;
            simple-audio-card,name = "TLV320AIC3110";
            simple-audio-card,format = "i2s";
            simple-audio-card,convert-rate = <48000>;
            simple-audio-card,mclk-fs = <256>;
 
            simple-audio-card,bitclock-master = <&snd_codec>;
            simple-audio-card,frame-master = <&snd_codec>;
 
            simple-audio-card,widgets =
                "Microphone", "Mic Jack",
                "Speaker", "External Speaker";
            simple-audio-card,routing =
                "External Speaker", "SPL",
                "External Speaker", "SPR",
                "MIC1LP", "Mic Jack",
                "MIC1LM", "Mic Jack";
 
            status = "okay";
 
            dailink0_master: simple-audio-card,cpu {
                sound-dai = <&i2s_clk_consumer>;
                dai-tdm-slot-num = <2>;
                dai-tdm-slot-width = <32>;
            };
 
            snd_codec: simple-audio-card,codec {
                sound-dai = <&tlv320aic3110>;
                clocks = <&mclk_external>;
                system-clock-direction-out = "out";
                system-clock-frequency = <12288000>; //*** added LAX
                mclk-fs = <256>; //*** added LAX
            };
        };
    };
 
    fragment@4 {
        target-path = "/";
        __overlay__ {
            mclk_external: mclk_external {
                compatible = "fixed-clock";
                #clock-cells = <0>;
                clock-frequency = <12288000>; // 12.288 MHz
                clock-output-names = "mclk";
            };
        };
    };
};
</syntaxhighlight>

== Explanation ==
After carefully reading the source code, I finally found the culprit of my issues. Even if the datasheet suggest I can bypass the PLL if use a proper frequency for MCLK (I chose 12.288Mhz and 11.2896Mhz which divided by 256 gives 48Khz and 41.1Khz), the device driver does not support any arbitrary frequency! They have a bunch of lookup tables for clock rates and playback and if your choice is not present, the driver will fail.

I modified the source code and added the proper lookups for my custom frequencies

Code: Select all

 /* ADC dividers can be disabled by configuring them to 0 */
 static const struct aic31xx_rate_divs aic31xx_divs[] = {
 ...
    /* 11.2896 MHz (11289600 Hz) */
    { 11289600, 44100, 1, 7, 6800, 128, 8, 2, 128, 8, 2},
    /* 12.288 MHz (12288000 Hz) */
    { 12288000, 44100,  1, 7, 5264, 128,   8,  2,   128,   8,  2},
    /* 11.2896 MHz (11289600 Hz) */
    { 11289600, 48000,  1, 7, 6800, 128,   8,  2,   128,   8,  2},
    /* 12.288 MHz (12288000 Hz) */
    { 12288000, 48000,  1, 8, 1920, 128,   8,  2,   128,   8,  2},

After a fun fight with Ubuntu to compile this, lo and behold, everything plays!

Now for my project which involves an Iot device, I don't want to have to include an unsigned device driver that will need DKMS to install with every kernel update, I will redo my PCB hardware oscillator to use a natively supported frequency. I leave as an exercise to the people at TI to write a function that dynamically creates a lookup entry for a random frequency MCLK and playback combo!

{{Wiki}}