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
扬声器播放音乐
至此，音频调试 OK
