ADC add MCLK signal

[giseleznev 0]

I got I2S working with a PCM5102 codec (DAC), but in the next board I would like to use a board which requires MCLK (256*fs).

How to output MCLK as well additionally to BCLK/LRCLK?

[giseleznev 0]

Basically, I need to output clock signal to one of free gpio pins. It should be synced with other clocks of i2s. How can I do it ?

[giseleznev 0]

OK, I found:

i2s_8ch_mclk: i2s-8ch-mclk {
		rockchip,pins = <4 0 RK_FUNC_1 &pcfg_pull_none>;
};

Seems like I need this one to use in overlay to output mclk. How should I add it to a .dts file ?

[giseleznev 0]

For a simple test, I'm adding usage of i2s_8ch_mclk to a hifiberry dac overlay. I want to see not just i2s signal, but also master clock on pin 37 (phys num). There no master clock, just i2s for now. What am I doing wrong? Any ideas, please, help!
Overlay (Linux linaro-alip 4.4.194) :

#include <dt-bindings/pinctrl/rockchip.h>
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/clock/rk3399-cru.h>

/dts-v1/;
/plugin/;

/ {
	compatible = "rockchip,rk3399";

	fragment@0 {
		target-path = "/spdif-sound";
		__overlay__ {
			status = "disabled";
		};
	};

	fragment@1 {
		target-path = "/hdmi-dp-sound";
		__overlay__ {
			status = "disabled";
		};
	};

	fragment@2 {
		target = <&i2s0>;
		__overlay__ {
			assigned-clocks = <&cru SCLK_I2SOUT_SRC>;
            		assigned-clock-parents = <&cru SCLK_I2S0_8CH>;
			pinctrl-0 = <&i2s_8ch_mclk>, <&i2s0_8ch_bus>;
			status = "okay";
		};
	};

	fragment@3 {
		target-path = "/";
		__overlay__ {
			pcm5102a-codec {
				#sound-dai-cells = <0>;
				compatible = "ti,pcm5102a";
				status = "okay";
			};
		};
	};

	fragment@4 {
        	target = <&pinctrl>;
        	__overlay__ {
            		i2s0 {
                		i2s_8ch_mclk: i2s-8ch-mclk {
                    			// GPIO4_A0 - RK3399 I2S_CLK
                    			rockchip,pins = <4 21 1 &pcfg_pull_none>;
                		};
            		};
		};
    	};

	fragment@5 {
		target-path = "/sound-ext-card";
		__overlay__ {
			compatible = "hifiberry,hifiberry-dac";
			i2s-controller = <&i2s0>;
			status = "okay";
		};
	};
};

 

Edited May 24, 2023 by giseleznev

[giseleznev 0]

@tooz, Any ideas, please ?

[tooz 54]

hello @giseleznev, 

1. which adc are you using? do you have a product link so i can check the spec?

2. may i have a look at how the sound card is connected to tinker board 2s?

[giseleznev 0]

ADC is pcm1804, but it doesn't matter, as basically all I need is master clock signal, taken from i2s. I can test master clock adding with a DAC pcm5102. That's what I'm doing. 

I'm using hifiberry-dac-overlay with changes above, and in addition to usual i2s I want to get master clock on one of the pins. As I think, it can be done with adding i2s-8ch-mclk to an overlay. The question is how ?

pcm 5102 connected and it sounds OK, I'm probing additional pin with oscillograph, hoping to get master clock

Edited May 25, 2023 by giseleznev