[参考译文] TLV320AIC3110：限制最大音量级别

您好！ Jesús

如果您想限制 最大音量，并通过 alsamixer 调节音量。 您不需要重写寄存器、因为每次您调整 kcontrol 时、都会进行修改。 我的建议是重写 kcontrol 的最大值。

请参阅以下几行代码。

static const struct snd_kcontrol_new common31xx_snd_controls[] = {
	SOC_DOUBLE_R_S_TLV("DAC Playback Volume", AIC31XX_LDACVOL,
			   AIC31XX_RDACVOL, 0, -127, 48, 7, 0, dac_vol_tlv),

	SOC_DOUBLE_R("HP Driver Playback Switch", AIC31XX_HPLGAIN,
		     AIC31XX_HPRGAIN, 2, 1, 0),
	SOC_DOUBLE_R_TLV("HP Driver Playback Volume", AIC31XX_HPLGAIN,
			 AIC31XX_HPRGAIN, 3, 0x09, 0, hp_drv_tlv),

	SOC_DOUBLE_R_TLV("HP Analog Playback Volume", AIC31XX_LANALOGHPL,
			 AIC31XX_RANALOGHPR, 0, 0x7F, 1, hp_vol_tlv),

	/* HP de-pop control: apply power not immediately but via ramp
	 * function with these psarameters. Note that power up sequence
	 * has to wait for this to complete; this is implemented by
	 * polling HP driver status in aic31xx_dapm_power_event()
	 */
	SOC_ENUM("HP Output Driver Power-On time", hp_poweron_time_enum),
	SOC_ENUM("HP Output Driver Ramp-up step", hp_rampup_step_enum),

	SOC_ENUM("Volume Soft Stepping", vol_soft_step_mode_enum),
};

static const struct snd_kcontrol_new aic31xx_snd_controls[] = {
	SOC_SINGLE_TLV("ADC Fine Capture Volume", AIC31XX_ADCFGA, 4, 4, 1,
		       adc_fgain_tlv),

	SOC_SINGLE("ADC Capture Switch", AIC31XX_ADCFGA, 7, 1, 1),
	SOC_DOUBLE_R_S_TLV("ADC Capture Volume", AIC31XX_ADCVOL, AIC31XX_ADCVOL,
			   0, -24, 40, 6, 0, adc_cgain_tlv),

	SOC_SINGLE_TLV("Mic PGA Capture Volume", AIC31XX_MICPGA, 0,
		       119, 0, mic_pga_tlv),
};

static const struct snd_kcontrol_new aic311x_snd_controls[] = {
	SOC_DOUBLE_R("Speaker Driver Playback Switch", AIC31XX_SPLGAIN,
		     AIC31XX_SPRGAIN, 2, 1, 0),
	SOC_DOUBLE_R_TLV("Speaker Driver Playback Volume", AIC31XX_SPLGAIN,
			 AIC31XX_SPRGAIN, 3, 3, 0, class_D_drv_tlv),

	SOC_DOUBLE_R_TLV("Speaker Analog Playback Volume", AIC31XX_LANALOGSPL,
			 AIC31XX_RANALOGSPR, 0, 0x7F, 1, sp_vol_tlv),
};

 snd_kcontrol_new 的结构 将创建您在 alsamixer 中使用的 kcontrol，请参见每个宏的定义。 例如、检查 SOC_DOUBLE_R_TLV 和  SOC_DOUBLE_R_S_TLV 的定义、 Xmax 对应于寄存器设置的最大值、因此对 Xmax 进行限制、您应该限制最大音量。 为了控制扬声器的输出、您应该 修改 "Speaker Driver Playback Volume (扬声器驱动程序 播放音量)"和"DAC Playback Volume (DAC 播放音量)"。

#define SOC_DOUBLE_R_TLV(xname, reg_left, reg_right, xshift, xmax, xinvert, tlv_array) \
{	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = (xname),\
	.access = SNDRV_CTL_ELEM_ACCESS_TLV_READ |\
		 SNDRV_CTL_ELEM_ACCESS_READWRITE,\
	.tlv.p = (tlv_array), \
	.info = snd_soc_info_volsw, \
	.get = snd_soc_get_volsw, .put = snd_soc_put_volsw, \
	.private_value = SOC_DOUBLE_R_VALUE(reg_left, reg_right, xshift, \
					    xmax, xinvert) }

#define SOC_DOUBLE_R_S_TLV(xname, reg_left, reg_right, xshift, xmin, xmax, xsign_bit, xinvert, tlv_array) \
{	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = (xname),\
	.access = SNDRV_CTL_ELEM_ACCESS_TLV_READ |\
		 SNDRV_CTL_ELEM_ACCESS_READWRITE,\
	.tlv.p = (tlv_array), \
	.info = snd_soc_info_volsw, \
	.get = snd_soc_get_volsw, .put = snd_soc_put_volsw, \
	.private_value = SOC_DOUBLE_R_S_VALUE(reg_left, reg_right, xshift, \
					    xmin, xmax, xsign_bit, xinvert) }

我希望这些信息能有所帮助、请告诉我这是否可行。

谢谢

凯文·卢