Stm32mp157 wm8960 audio driver debugging notes

This debugging wm8960 The audio driver has encountered many pits , After several days of research, I finally debugged .

Drive debugging steps

Whether the driver can be loaded successfully is the first step of debugging , It is also one of the most critical steps .
1. Check the hardware schematic diagram :

2. Open the corresponding device tree （stm32mp157a-xxx.dtsi）:
because wm8960 It's mount to I2C4 On , So in the device tree I2C4 Add on node wm8960 Device node .

wm8960: [email protected]1a {
    
        compatible = "wlf,wm8960";
        reg = <0x1a>;
        #sound-dai-cells = <0>;
        status = "okay";
		wlf,shared-lrclk;
	 	clocks = <&sai2a>;
		clock-names = "mclk";
	        port {
    
	            #address-cells = <1>;
	            #size-cells = <0>;
		wm8960_tx_endpoint: [email protected]0 {
    
						reg = <0x0>;
						remote-endpoint = <&sai2b_endpoint>;
						frame-master;
						bitclock-master;
					};
	
		wm8960_rx_endpoint: [email protected]1 {
    
						reg = <0x1>;
						remote-endpoint = <&sai2a_endpoint>;
						frame-master;
						bitclock-master;
					};
	        };
    };

Of the nodes clocks =< sai2a > You need to look at the schematic diagram and use SAI2A still SAI2B Master clock .

3.SAI2 To configure ：

&sai2 {
    
    clocks = <&rcc SAI2>, <&rcc PLL3_Q>, <&rcc PLL3_R>;
    clock-names = "pclk", "x8k", "x11k";
    pinctrl-names = "default", "sleep";
    pinctrl-0 = <&sai2a_pins_a>, <&sai2b_pins_b>;
    pinctrl-1 = <&sai2a_sleep_pins_a>, <&sai2b_sleep_pins_b>;
    status = "okay";

    sai2a: audio-[email protected]4400b004 {
    
    dma-names = "rx";
	#clock-cells = <0>;
        clocks = <&rcc SAI2_K>;
        clock-names = "sai_ck";
        status = "okay";

        sai2a_port: port {
    
            sai2a_endpoint: endpoint {
    
                remote-endpoint = <&wm8960_rx_endpoint>;
                format = "i2s";
                mclk-fs = <256>; 
                dai-tdm-slot-num = <2>;
                dai-tdm-slot-width = <16>;
            };
        };
    };
    sai2b: audio-[email protected]4400b024 {
    
        dma-names = "tx";
        st,sync = <&sai2a 2>;
        clocks = <&rcc SAI2_K>, <&sai2a>;
        clock-names = "sai_ck", "MCLK";
        status = "okay";
        sai2b_port: port {
    
            sai2b_endpoint: endpoint {
    
                remote-endpoint = <&wm8960_tx_endpoint>;
                format = "i2s";
                mclk-fs = <256>;
                dai-tdm-slot-num = <2>;
                dai-tdm-slot-width = <16>;
            };
        };
    };
};

The most important thing is sai2a,sai2b I / O problem of , The above schematic diagram describes sai2a As ADC(capture),sai2b As DAC(playback), therefore , here sai2a Nodes in the dma-names = ‘tx’,sai2b It is dma-names = ‘rx’, And then there is st,sync = <&sai2a 2>;
Here you can refer to the kernel source code path :Documentation/devicetree/bindings/sound/st,stm32-sai.txt file

4.sound Node configuration

  sound: sound {
    
        compatible = "audio-graph-card";
        label = "wm8960-audio";
       	mclk-fs = <256>;
	dai-format = "i2s";
	widgets =
            "Microphone", "Mic Jack",
            "Line", "Line In",
            "Line", "Line Out",
            "Speaker", "Speaker",
            "Headphone", "Headphone Jack";
        routing =
            "Headphone Jack", "HP_L",
            "Headphone Jack", "HP_R",
            "Speaker", "SPK_LP",
            "Speaker", "SPK_LN",
            "Speaker", "SPK_RP",
            "Speaker", "SPK_RN",
            "LINPUT1", "MICB",
            "LINPUT3", "MICB";
        dais = <&sai2a_port &sai2b_port>; 
        status = "okay";
    };

5. Configure pins (stm32mp15-pinctrl.dtsi)：

sai2a_pins_a: sai2a-0 {
    
		pins {
    
			pinmux = <STM32_PINMUX('I', 6, AF10)>; /* SAI2_SD_A */		 
			bias-disable;
			drive-push-pull;
			slew-rate = <0>;
		};
	};

	sai2a_sleep_pins_a: sai2a-1 {
    
		pins {
    
			pinmux = <STM32_PINMUX('I', 6, ANALOG)>; /* SAI2_SD_A */
			
		};
	};
	sai2b_pins_b: sai2b-2 {
    
		pins {
    
			pinmux = <STM32_PINMUX('E', 11, AF10)>, /* SAI2_SD_B */
				 <STM32_PINMUX('I', 5, AF10)>, /* SAI2_SCK_A */ 
				 <STM32_PINMUX('I', 7, AF10)>, /* SAI2_FS_A */
				 <STM32_PINMUX('E', 0, AF10)>; /* SAI2_MCLK_A */
				bias-disable;
				drive-push-pull;
				slew-rate = <0>;
		};
	};

	sai2b_sleep_pins_b: sai2b-3 {
    
		pins {
    
			pinmux = <STM32_PINMUX('E', 11, ANALOG)>, /* SAI2_SD_B */
				  <STM32_PINMUX('I', 5, ANALOG)>, /* SAI2_SCK_A */ 
				 <STM32_PINMUX('I', 7, ANALOG)>, /* SAI2_FS_A */
				 <STM32_PINMUX('E', 0, ANALOG)>; /* SAI2_MCLK_A */
				
		};
	};

6. View startup information :

If the above start printing message appears , prove wm8960 Driver loading succeeded . Next, let's see if there are any sound card nodes .

[[email protected]]:~# ls /dev/snd/
by-path/   controlC0  pcmC0D0c   pcmC0D1p   timer

pcmC0D0c It's a recording device
pcmC0D1p It's a playback device

[[email protected]]:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: wm8960audio [wm8960-audio], device 1: 4400b024.audio-controller-wm8960-hifi wm8960-hifi-1 [4400b024.audio-controller-wm8960-hifi wm8960-hifi-1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
[[email protected]]:~# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: wm8960audio [wm8960-audio], device 0: 4400b004.audio-controller-wm8960-hifi wm8960-hifi-0 [4400b004.audio-controller-wm8960-hifi wm8960-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Sound card 0, equipment 0 --> It's a recording device
Sound card 0, equipment 1 --> It's a playback device

7. Trouble problem
If you use the command :aplay xxx.wav, Always stuck on the command line without ending , There is no error message , You need to check the schematic diagram , Whether it corresponds to the configuration problem of the device tree .
If aplay xxx.wav , The following error message appears :
[[email protected]]:~# aplay -Dhw:0.0 /usr/share/sounds/alsa/Rear_Right.wav
ALSA lib …/…/…/alsa-lib-1.2.1.2/src/pcm/pcm_hw.c:1829:(_snd_pcm_hw_open) Invalid value for card
aplay: main:828: audio open error: No such device
Need to use aplay -l Check the playing device number , see /etc/asound.conf Whether the configuration is correct . You can use commands aplay -Dhw:0.1 xxx.wav To specify the device to play .

asound.conf The configuration file

Once the driver was loaded successfully , Just no sound , After checking the hardware and driver, there is no problem ,alsamixer Also set the sound level , Not yet. , Find out asound.conf It will have a certain impact .

pcm.dmix_44100{
    
type dmix
ipc_key 5678293
ipc_key_add_uid yes
slave{
    
pcm "hw:0,0"
period_time 40000
buffer_time 360000
format S16_LE
rate 44100
}
}
pcm.!dsnoop_44100{
    
type dsnoop
ipc_key 5778293
ipc_key_add_uid yes
slave{
    
pcm "hw:0,1"
period_time 40000
buffer_time 360000
format S16_LE
rate 44100
}
}
pcm.asymed{
    
type asym
playback.pcm "dmix_44100"
capture.pcm "dsnoop_44100"
}

pcm.dsp0{
    
type plug
slave.pcm "asymed"
}

pcm.!default{
    
type plug
route_policy "average"
slave.pcm "asymed"
}

ctl.!default{
    
type hw
card 0
}

ctl.mixer0{
    
type hw
card 0
}

Experience

When there is a problem , Don't worry , Driving the print message will help you find the reason for the failure , If it doesn't work , You can refer to the successful cases of others , Change the hardware circuit to the same , See if it's a hardware or chip problem .

Enclosed wm8960 Driver files and asound.conf Link to your profile :wm8960 Driver files and asound.conf The configuration file