前言

今天，调试一下音频

硬件焊接

硬件部分核心是 LM4871 音频功放芯片

对于 SOC 来讲很简单，就一个引脚 HPOUTL（单声道）；对于扬声器来讲也很简单，就两个引脚，插上就可以了。
另外一个关键点是电容和电阻要焊到位，有没有噪音，音质好坏，全屏电容电阻打下手。

设备树

arch/arm/boot/dts/sun8i-v3s.dtsi

        dma: dma-controller@01c02000 {
            compatible = "allwinner,sun8i-v3s-dma";
            reg = <0x01c02000 0x1000>;
            interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
            clocks = <&ccu CLK_BUS_DMA>;
            resets = <&ccu RST_BUS_DMA>;
            #dma-cells = <1>;
        };


        codec_analog: codec-analog@01c23000 {
            compatible = "allwinner,sun8i-v3s-codec-analog";
            reg = <0x01c23000 0x4>;
        };


        codec: codec@01c22c00 {
            #sound-dai-cells = <0>;
            compatible = "allwinner,sun8i-v3s-codec";
            reg = <0x01c22c00 0x400>;
            interrupts = <GIC_SPI 29 IRQ_TYPE_LEVEL_HIGH>;
            clocks = <&ccu CLK_BUS_CODEC>, <&ccu CLK_AC_DIG>;
            clock-names = "apb", "codec";
            resets = <&ccu RST_BUS_CODEC>;
            dmas = <&dma 15>, <&dma 15>;
            dma-names = "rx", "tx";
            allwinner,codec-analog-controls = <&codec_analog>;
            status = "disabled";
        };

arch/arm/boot/dts/sun8i-v3s-licheepi-zero-dock.dts

&codec {
    allwinner,audio-routing =
        "Headphone", "HP",
        "Headphone", "HPCOM",
        "MIC1", "Mic",
        "Mic",  "HBIAS";
    status = "okay";
};

驱动

使能内核编译选项

> Device Drivers > Sound card support > Advanced Linux Sound Architecture > ALSA for SoC audio support > Allwinner SoC Audio support
<*> Allwinner sun8i Codec Analog Controls Support

应用程序

参照《v3S驱动音频》移植 alsa-lib 和 alsa-utils

测试

1、查看设备信息

# ls /dev/snd/
controlC0  pcmC0D0c   pcmC0D0p   timer
#
# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: Codec [V3s Audio Codec], device 0: CDC PCM Codec-0 [CDC PCM Codec-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
# 

设备驱动正常

2、取消静音

# ./amixer -c 0 sset 'Headphone',0 100% unmute

3、调节音量

4、播放音乐

# aplay dlj-yldbwdx.wav 
Playing WAVE 'dlj-yldbwdx.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo

至此，音频调试 OK