Hi!

I am working on a project in which audio is transmitted over the I2S bus to TAS6424-Q1 chips. I am using the Radxa Rock S0 board, the latest stable Armbinan 6.6 kernel and an additionally compiled dummy-codec module. 

1. If I use the following overlay

 

// Definitions for 8-ch-output
/dts-v1/;
/plugin/;

/ {
        compatible = "radxa,rockpis", "rockchip,rk3308";

        fragment@0 {
                target = <&i2s_8ch_0>;

                __overlay__ {
                        #sound-dai-cells = <0>;
                        rockchip,clk-trm = <1>;
                        status = "okay";
                        };
               };

        fragment@1 {
                target = <&i2s_8ch_2>;

                __overlay__ {
                        #sound-dai-cells = <0>;
                        status = "disabled";
                        };
               };

        fragment@2 {
                target = <&acodec>;

                __overlay__ {
                        #sound-dai-cells = <0>;
                        status = "disabled";
                        };
               };

        fragment@3 {
                target-path = "/";

                __overlay__ {
                        mycodec: multi-ch-out {
                                #sound-dai-cells = <0>;
                                compatible = "rockchip,dummy-codec";
                                status = "okay";
                                };

                        sound_i2s {
                                simple-audio-card,name = "multi-ch-card";
                                compatible = "simple-audio-card";
                                simple-audio-card,format = "i2s";
                                simple-audio-card,mclk-fs = <128>;
                                status = "okay";

                                cpu_dai: simple-audio-card,cpu {
                                sound-dai = <&i2s_8ch_0>;
                                };

                                codec_dai: simple-audio-card,codec {
                                sound-dai = <&mycodec>;
                                };
                         };
                };
        };
};

and when I try to play something (for example, speaker-test -from 8), I get a hung process that cannot even be killed with "kill -9". I am attaching the error log. But!

2. If I modify my rk3308-rocks-0.dts file as follow without any overlay:

...
i2s@ff300000 {
		status = "okay";
		phandle = <0x79>;
...
i2s@ff320000 {
		status = "disabled";
...

	sound {
				compatible = "simple-audio-card";
                #sound-dai-cells = < 0 >;
				simple-audio-card,format = "i2s";
				simple-audio-card,mclk-fs = <0x100>;
				simple-audio-card,name = "OUT8CH";
				simple-audio-card,bitclock-master = <&cpu_dai>;
				simple-audio-card,frame-master = <&cpu_dai>;
				simple-audio-card,status = "okay";
                
				cpu_dai: simple-audio-card,cpu {
					sound-dai = <0x79>;
						};
						simple-audio-card,codec {
							sound-dai = <&dummy_tdm_codec>;
						};
			};

        dummy_tdm_codec: dummy-codec {
                status = "okay";
                compatible = "rockchip,dummy-codec";
//				clocks = <0x02 0x4c>;
//				clock-names = "mclk_tx";
//				pinctrl-names = "default";
//				pinctrl-0 = <0x4a>;
                #sound-dai-cells = < 0 >;
                phandle = < 0x139 >;
                };

BCK, LRCK and DATA signals are transmitted without problems, but I can't get the MCLK signal from pin 35 of the board (GPIO2_A4 or I2S0_8CH_MCLK) in any way, even if you uncomment the lines with clocks and pinctrl..

 

My project will collapse without a working mclk. Please, help!

err.log

Edited October 26, 20241 yr by Виктор Хомченко

I answer myself!

1. Decompile rk3308-rock-s0.dtb to rk3308-rock-s0.dts. Edit...

2. Find i2s@ff300000 edit: Remove last 0x4a from pinctrl-0 string:

pinctrl-0 = <0x3e 0x3f 0x40 0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49>;
status = "okay";

3. Comment out the node completely "acodec-sound"

4. Edit node "sound":

        sound {
                compatible = "simple-audio-card";
                simple-audio-card,format = "i2s";
                simple-audio-card,mclk-fs = <0x100>; //256 decimal
                simple-audio-card,name = "i2s_8ch_0";
                simple-audio-card,bitclock-master = <0x7a>; // &i2s@ff300000
            	simple-audio-card,frame-master = <0x7a>; // &i2s@i2s@ff300000

                simple-audio-card,dai-link@1 {
                        cpu {
                                sound-dai = <0x7a>; //i2s@i2s@ff300000
                        };

                        codec {
                                sound-dai = <&dummy_tdm_codec>;
                        };
                };
        };

        dummy_tdm_codec: dummy-codec {
                status = "okay";
                compatible = "rockchip,dummy-codec";
                #sound-dai-cells = < 0 >;
                clocks = <&cru SCLK_I2S0_8CH_TX_OUT>; //or <0x02 0x4d>
		clock-names = "mclk";
		pinctrl-names = "default";
		pinctrl-0 = <&i2s_8ch_0_mclk>; //or <0x4a>
                };

5. Do't forget to compile dummy-codec module! (make, make install, depmod)

6. Copy rk3308-rock-s0.dtb to /boot/dtb/rockchip/

7. Reboot

 

Voila, all four I2S channels should work and MCLK on pin 35 should be!

dummy-codec.zip