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<div class=" wh_topic_content body "><main role="main"><article class="- topic/topic concept/concept topic concept" role="article" aria-labelledby="ariaid-title1">
<span class="edit-link" style="font-size:12px; opacity:0.6; text-align:right; vertical-align:middle"><a target="_blank" title="Edit this document" href="http://172.16.35.88/tasks/jdssno1uvvbf2mltu9kb9v3if05d5gopuakboe8hlud18rma/edit/F:/aicdita/aicdita-cn/topics/sdk/audio_codec/audio-codec-key_procedures.dita">Edit online</a></span><h1 class="- topic/title title topictitle1" id="ariaid-title1">关键流程设计</h1>
<div class="date inPage">15 Jan 2024</div><div style="color: gray;">
Read time: 12 minute(s)
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<div class="- topic/body concept/conbody body conbody">
<section class="- topic/section section" id="audio_codec_key_procedures__section_hv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_hv1_h1n_d1c"><h2 class="- topic/title title sectiontitle">初始化流程</h2>
<p class="- topic/p p" data-ofbid="d57970e38__20250123155202">AudioCodec 模块的初始化流程如下：</p>
<ol class="- topic/ol ol" id="audio_codec_key_procedures__ol_iv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__ol_iv1_h1n_d1c">
<li class="- topic/li li" data-ofbid="d57970e43__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e45__20250123155202">释放 clock 和 reset 信号</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e49__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e51__20250123155202">释放 AudioCodec 模块的全局复位信号</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e55__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e57__20250123155202">配置 playback 和 capture 的 DMA 传输参数</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e61__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e63__20250123155202">注册 codec 端 component driver 和 codec_dai driver</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e67__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e69__20250123155202">注册 platform 端 component driver 和 cpu_dai driver</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e74__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e76__20250123155202">创建声卡设备，初始化声卡的各个参数实例</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e80__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e82__20250123155202">注册声卡</p>
</li>
</ol>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_jv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_jv1_h1n_d1c"><h2 class="- topic/title title sectiontitle">音频通路设置</h2><p class="- topic/p p" data-ofbid="d57970e91__20250123155202">在 AudioCodec 驱动中，非常重要的环节是音频通路的设置，音频通路是音频数据的流通方向，音频通路设置的正确与否关系到声卡是否能正常工作。Linux 内核中，引入了 DAPM 机制，对音频通路进行动态的上下电管理，降低系统的功耗。AudioCodec 的音频通路设计如下：</p><div class="- topic/p p" data-ofbid="d57970e93__20250123155202"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="audio_codec_key_procedures__image_kv1_h1n_d1c" src="../../../images/audio/audio_data_path.png" alt="data_path"/></div><br/></div><p class="- topic/p p" data-ofbid="d57970e99__20250123155202">如上图所示，在 capture 端，左右声道的音频信号依次经过 DMICI/F、DF、HPF、DVC，输出的 OUT 音频信号可以直接存储到 RXFIFO 中，或是经过混音器 MIX0 或 MIX1 直接输出到 playback 端。capture 通路中，HPF 和 DVC 都可以 bypass，音频信号可以不经过这两个模块的处理，直接旁路到下一个模块。</p><p class="- topic/p p" data-ofbid="d57970e101__20250123155202">在 playback 端，MIX0 和 MIX1 的音频输入信号，可以来自 TXFIFO，也可以来自 OUT。MIX0 和 MIX1 的输出信号依次经过 DVC、IF、FADE、SDM、PWM 输出，实现音频的播放功能。playback 通路中，DVC 和 FADE 都可以 bypass，音频信号可以不经过这两个模块的处理，直接旁路到下一个模块。</p><p class="- topic/p p" data-ofbid="d57970e103__20250123155202">capture 端的音频通路如下图所示：</p><div class="- topic/p p" data-ofbid="d57970e105__20250123155202"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="audio_codec_key_procedures__image_lv1_h1n_d1c" src="../../../images/audio/capture_data_path.png" width="672" alt="capture_data_path"/></div><br/></div><p class="- topic/p p" data-ofbid="d57970e111__20250123155202">playback 端的音频通路如下图所示：</p><div class="- topic/p p" data-ofbid="d57970e113__20250123155202"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="audio_codec_key_procedures__image_mv1_h1n_d1c" src="../../../images/audio/playback_data_path.png" width="672" alt="playback_data_path"/></div><br/></div></section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_nv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_nv1_h1n_d1c"><h2 class="- topic/title title sectiontitle">音频通路的注册</h2>
<p class="- topic/p p" data-ofbid="d57970e125__20250123155202">在 ALSA 的 DAPM 中，音频通路上的结点用 widget 表示，widget 可以认为是对音频控件的进一步封装，它把音频控件和电源管理进行了结合，同时还具备音频路径的连接功能。实现音频通路的注册，需要以下几个步骤：</p>
<ol class="- topic/ol ol" id="audio_codec_key_procedures__ol_ov1_h1n_d1c" data-ofbid="audio_codec_key_procedures__ol_ov1_h1n_d1c">
<li class="- topic/li li" data-ofbid="d57970e130__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e132__20250123155202">先把音频路径中的结点初始化为 widget 类型的实例：<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_kbq_31n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_kbq_31n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_dapm_widget aic_codec_dapm_widgets[] = {
SND_SOC_DAPM_ADC(<span class="hl-string">"DMICIF"</span>, <span class="hl-string">"Capture-dmic"</span>, RX_DMIC_IF_CTRL_REG,
RX_DMIC_IF_EN, <span class="hl-number">0</span>),
<em class="hl-comment">/* MUX */</em>
SND_SOC_DAPM_MUX(<span class="hl-string">"PWM ch0"</span>, TX_PWM_CTRL_REG, TX_PWM0_EN,
<span class="hl-number">0</span>, &amp;pwm0_output_mux),
SND_SOC_DAPM_MUX(<span class="hl-string">"PWM ch1"</span>, TX_PWM_CTRL_REG, TX_PWM1_EN,
<span class="hl-number">0</span>, &amp;pwm1_output_mux),
SND_SOC_DAPM_MUX(<span class="hl-string">"HPF"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>, &amp;hpf_mux),
SND_SOC_DAPM_MUX(<span class="hl-string">"FADE ch0"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>, &amp;fade0_mux),
SND_SOC_DAPM_MUX(<span class="hl-string">"FADE ch1"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>, &amp;fade1_mux),
SND_SOC_DAPM_MUX(<span class="hl-string">"ADC HPF"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>, &amp;adc_hpf_mux),
<em class="hl-comment">/* Sigma-Delta Modulation */</em>
SND_SOC_DAPM_DAC(<span class="hl-string">"SDM ch0"</span>, <span class="hl-string">"Playback"</span>, TX_SDM_CTRL_REG,
TX_SDM_CH0_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_DAC(<span class="hl-string">"SDM ch1"</span>, <span class="hl-string">"Playback"</span>, TX_SDM_CTRL_REG,
TX_SDM_CH1_EN, <span class="hl-number">0</span>),
<em class="hl-comment">/* PGA */</em>
SND_SOC_DAPM_PGA(<span class="hl-string">"DVC 0"</span>, ADC_DVC0_CTRL_REG, ADC_DVC0_CTRL_DVC0_EN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_PGA(<span class="hl-string">"DVC 1"</span>, RX_DVC_<span class="hl-number">1</span>_<span class="hl-number">2</span>_CTRL_REG, RX_DVC1_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_PGA(<span class="hl-string">"DVC 2"</span>, RX_DVC_<span class="hl-number">1</span>_<span class="hl-number">2</span>_CTRL_REG, RX_DVC2_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_PGA(<span class="hl-string">"DVC 3"</span>, TX_DVC_<span class="hl-number">3</span>_<span class="hl-number">4</span>_CTRL_REG, TX_DVC3_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_PGA(<span class="hl-string">"DVC 4"</span>, TX_DVC_<span class="hl-number">3</span>_<span class="hl-number">4</span>_CTRL_REG, TX_DVC4_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_PGA(<span class="hl-string">"PGA"</span>, ADC_CTL1_REG, ADC_CTL1_PGA_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
<em class="hl-comment">/* Mixer */</em>
SND_SOC_DAPM_MIXER(<span class="hl-string">"MIXER0"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>,
aic_codec_mixer0_controls,
ARRAY_SIZE(aic_codec_mixer0_controls)),
SND_SOC_DAPM_MIXER(<span class="hl-string">"MIXER1"</span>, SND_SOC_NOPM, <span class="hl-number">0</span>, <span class="hl-number">0</span>,
aic_codec_mixer1_controls,
ARRAY_SIZE(aic_codec_mixer1_controls)),
<em class="hl-comment">/* SUPPLY */</em>
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"FADE"</span>, FADE_CTRL0_REG, FADE_CTRL0_EN, <span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"IF"</span>, TX_PLAYBACK_CTRL_REG, TX_PLAYBACK_IF_EN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"Mic Bias"</span>, ADC_CTL1_REG, ADC_CTL1_MBIAS_EN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"TX GLBEN"</span>, GLOBE_CTL_REG, GLOBE_TX_GLBEN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"RX GLBEN"</span>, GLOBE_CTL_REG, GLOBE_RX_GLBEN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_DAC(<span class="hl-string">"IF ch0"</span>, <span class="hl-string">"Playback"</span>, TX_PLAYBACK_CTRL_REG,
TX_IF_CH0_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_DAC(<span class="hl-string">"IF ch1"</span>, <span class="hl-string">"Playback"</span>, TX_PLAYBACK_CTRL_REG,
TX_IF_CH1_EN, <span class="hl-number">0</span>),
<em class="hl-comment">/* AIF OUT */</em>
SND_SOC_DAPM_AIF_OUT(<span class="hl-string">"AUDOUTL"</span>, <span class="hl-string">"Playback"</span>, <span class="hl-number">0</span>, TXFIFO_CTRL_REG,
TXFIFO_CH0_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_AIF_OUT(<span class="hl-string">"AUDOUTR"</span>, <span class="hl-string">"Playback"</span>, <span class="hl-number">1</span>, TXFIFO_CTRL_REG,
TXFIFO_CH1_EN, <span class="hl-number">0</span>),
<em class="hl-comment">/* AIF IN */</em>
SND_SOC_DAPM_AIF_IN(<span class="hl-string">"DMICOUTL"</span>, <span class="hl-string">"Capture-dmic"</span>, <span class="hl-number">0</span>, DMIC_RXFIFO_CTRL_REG,
DMIC_RXFIFO_CH0_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_AIF_IN(<span class="hl-string">"DMICOUTR"</span>, <span class="hl-string">"Capture-dmic"</span>, <span class="hl-number">1</span>, DMIC_RXFIFO_CTRL_REG,
DMIC_RXFIFO_CH1_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_AIF_IN(<span class="hl-string">"ADCOUT"</span>, <span class="hl-string">"Capture-adc"</span>, <span class="hl-number">0</span>, ADC_RXFIFO_CTRL_REG,
ADC_RXFIFO_EN, <span class="hl-number">0</span>),
<em class="hl-comment">/* ADC */</em>
SND_SOC_DAPM_ADC(<span class="hl-string">"ADC"</span>, <span class="hl-string">"ADC Capture-adc"</span>, ADC_CTL1_REG,
ADC_CTL1_ADC_EN, <span class="hl-number">0</span>),
SND_SOC_DAPM_INPUT(<span class="hl-string">"AMIC"</span>),
SND_SOC_DAPM_INPUT(<span class="hl-string">"DMIC"</span>),
SND_SOC_DAPM_OUTPUT(<span class="hl-string">"SPK_OUT0"</span>),
SND_SOC_DAPM_OUTPUT(<span class="hl-string">"SPK_OUT1"</span>),
};</code></pre></div>
</li>
<li class="- topic/li li" data-ofbid="d57970e138__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e140__20250123155202">利用实例化的 widget 定义 route 信息。DAPM 中，利用 route 结构体表示两个 widget 的连接关系。struct snd_soc_dapm_route 按照
<em class="+ topic/ph hi-d/i ph i">{“目的 widget”, “控件”， “源 widget”}</em> 的方式进行定义。</p>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_xs5_31n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_xs5_31n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_dapm_route aic_codec_dapm_route[] = {
{<span class="hl-string">"DMICOUTL"</span>, NULL, <span class="hl-string">"RX GLBEN"</span>},
{<span class="hl-string">"DMICOUTR"</span>, NULL, <span class="hl-string">"RX GLBEN"</span>},
{<span class="hl-string">"DMICIF"</span>, NULL, <span class="hl-string">"DMIC"</span>},
{<span class="hl-string">"HPF"</span>, <span class="hl-string">"Bypass"</span>, <span class="hl-string">"DMICIF"</span>},
{<span class="hl-string">"HPF"</span>, <span class="hl-string">"HPF Enable"</span>, <span class="hl-string">"DMICIF"</span>},
{<span class="hl-string">"DVC 1"</span>, NULL, <span class="hl-string">"HPF"</span>},
{<span class="hl-string">"DVC 2"</span>, NULL, <span class="hl-string">"HPF"</span>},
{<span class="hl-string">"DMICOUTL"</span>, NULL, <span class="hl-string">"DVC 1"</span>},
{<span class="hl-string">"DMICOUTR"</span>, NULL, <span class="hl-string">"DVC 2"</span>},
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
{<span class="hl-string">"ADCOUT"</span>, NULL, <span class="hl-string">"RX GLBEN"</span>},
{<span class="hl-string">"AMIC"</span>, NULL, <span class="hl-string">"Mic Bias"</span>},
{<span class="hl-string">"PGA"</span>, NULL, <span class="hl-string">"AMIC"</span>},
{<span class="hl-string">"ADC"</span>, NULL, <span class="hl-string">"PGA"</span>},
{<span class="hl-string">"ADC HPF"</span>, <span class="hl-string">"Bypass"</span>, <span class="hl-string">"ADC"</span>},
{<span class="hl-string">"ADC HPF"</span>, <span class="hl-string">"HPF Enable"</span>, <span class="hl-string">"ADC"</span>},
{<span class="hl-string">"DVC 0"</span>, NULL, <span class="hl-string">"ADC HPF"</span>},
{<span class="hl-string">"ADCOUT"</span>, NULL, <span class="hl-string">"DVC 0"</span>},
#endif
{<span class="hl-string">"AUDOUTL"</span>, NULL, <span class="hl-string">"TX GLBEN"</span>},
{<span class="hl-string">"AUDOUTR"</span>, NULL, <span class="hl-string">"TX GLBEN"</span>},
<em class="hl-comment">/* MIXER */</em>
{<span class="hl-string">"MIXER0"</span>, <span class="hl-string">"audoutl switch"</span>, <span class="hl-string">"AUDOUTL"</span>},
{<span class="hl-string">"MIXER0"</span>, <span class="hl-string">"audoutr switch"</span>, <span class="hl-string">"AUDOUTR"</span>},
{<span class="hl-string">"MIXER0"</span>, <span class="hl-string">"dmicoutl switch"</span>, <span class="hl-string">"DMICOUTL"</span>},
{<span class="hl-string">"MIXER0"</span>, <span class="hl-string">"dmicoutr switch"</span>, <span class="hl-string">"DMICOUTR"</span>},
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
{<span class="hl-string">"MIXER0"</span>, <span class="hl-string">"adcout switch"</span>, <span class="hl-string">"ADCOUT"</span>},
#endif
{<span class="hl-string">"MIXER1"</span>, <span class="hl-string">"audoutl switch"</span>, <span class="hl-string">"AUDOUTL"</span>},
{<span class="hl-string">"MIXER1"</span>, <span class="hl-string">"audoutr switch"</span>, <span class="hl-string">"AUDOUTR"</span>},
{<span class="hl-string">"MIXER1"</span>, <span class="hl-string">"dmicoutl switch"</span>, <span class="hl-string">"DMICOUTL"</span>},
{<span class="hl-string">"MIXER1"</span>, <span class="hl-string">"dmicoutr switch"</span>, <span class="hl-string">"DMICOUTR"</span>},
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
{<span class="hl-string">"MIXER1"</span>, <span class="hl-string">"adcout switch"</span>, <span class="hl-string">"ADCOUT"</span>},
#endif
{<span class="hl-string">"FADE ch0"</span>, NULL, <span class="hl-string">"FADE"</span>},
{<span class="hl-string">"FADE ch1"</span>, NULL, <span class="hl-string">"FADE"</span>},
{<span class="hl-string">"IF ch0"</span>, NULL, <span class="hl-string">"IF"</span>},
{<span class="hl-string">"IF ch1"</span>, NULL, <span class="hl-string">"IF"</span>},
{<span class="hl-string">"DVC 3"</span>, NULL, <span class="hl-string">"MIXER0"</span>},
{<span class="hl-string">"IF ch0"</span>, NULL, <span class="hl-string">"DVC 3"</span>},
{<span class="hl-string">"FADE ch0"</span>, <span class="hl-string">"Bypass"</span>, <span class="hl-string">"IF ch0"</span>},
{<span class="hl-string">"FADE ch0"</span>, <span class="hl-string">"Fade Enable"</span>, <span class="hl-string">"IF ch0"</span>},
{<span class="hl-string">"SDM ch0"</span>, NULL, <span class="hl-string">"FADE ch0"</span>},
{<span class="hl-string">"PWM ch0"</span>, <span class="hl-string">"Single_ended"</span>, <span class="hl-string">"SDM ch0"</span>},
{<span class="hl-string">"PWM ch0"</span>, <span class="hl-string">"Differential"</span>, <span class="hl-string">"SDM ch0"</span>},
{<span class="hl-string">"SPK_OUT0"</span>, NULL, <span class="hl-string">"PWM ch0"</span>},
{<span class="hl-string">"DVC 4"</span>, NULL, <span class="hl-string">"MIXER1"</span>},
{<span class="hl-string">"IF ch1"</span>, NULL, <span class="hl-string">"DVC 4"</span>},
{<span class="hl-string">"FADE ch1"</span>, <span class="hl-string">"Bypass"</span>, <span class="hl-string">"IF ch1"</span>},
{<span class="hl-string">"FADE ch1"</span>, <span class="hl-string">"Fade Enable"</span>, <span class="hl-string">"IF ch1"</span>},
{<span class="hl-string">"SDM ch1"</span>, NULL, <span class="hl-string">"FADE ch1"</span>},
{<span class="hl-string">"PWM ch1"</span>, <span class="hl-string">"Single_ended"</span>, <span class="hl-string">"SDM ch1"</span>},
{<span class="hl-string">"PWM ch1"</span>, <span class="hl-string">"Differential"</span>, <span class="hl-string">"SDM ch1"</span>},
{<span class="hl-string">"SPK_OUT1"</span>, NULL, <span class="hl-string">"PWM ch1"</span>},
};</code></pre>
</li>
<li class="- topic/li li" data-ofbid="d57970e150__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e152__20250123155202">将上面定义的两个数组赋值给 codec 的 component
driver<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_d1x_k1n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_d1x_k1n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_component_driver aic_codec_component = {
.controls = aic_codec_controls,
.num_controls = ARRAY_SIZE(aic_codec_controls),
.dapm_widgets = aic_codec_dapm_widgets,
.num_dapm_widgets = ARRAY_SIZE(aic_codec_dapm_widgets),
.dapm_routes = aic_codec_dapm_route,
.num_dapm_routes = ARRAY_SIZE(aic_codec_dapm_route),
.idle_bias_on = <span class="hl-number">1</span>,
.use_pmdown_time = <span class="hl-number">1</span>,
.endianness = <span class="hl-number">1</span>,
.non_legacy_dai_naming = <span class="hl-number">1</span>,
};</code></pre></div>
</li>
<li class="- topic/li li" data-ofbid="d57970e158__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e160__20250123155202">调用 component，完成音频路径的注册</p>
</li>
</ol>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_vv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_vv1_h1n_d1c"><h2 class="- topic/title title sectiontitle">音频控件设置</h2>
<p class="- topic/p p" data-ofbid="d57970e171__20250123155202">音频通路是音频数据流通的路径，而音频控件是负责音量大小的调节，以及一些开关的控制等功能。AudioCodec 的音频控件有 DVC 的音量调节，DVC、HPF、FADE 旁路选择，MIX 的增益使能，以及 DMICI/F 数据交换开关等。与音频通路的 widget 不同，音频控件一般是不具有动态上下电控制功能的。音频控件的注册需要三个步骤：</p>
<ol class="- topic/ol ol" id="audio_codec_key_procedures__ol_wv1_h1n_d1c" data-ofbid="audio_codec_key_procedures__ol_wv1_h1n_d1c">
<li class="- topic/li li" data-ofbid="d57970e176__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e178__20250123155202">定义 new 类型的音频控件<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_exg_41n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_exg_41n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_kcontrol_new aic_codec_controls[] = {
SOC_DOUBLE_TLV(<span class="hl-string">"DMICIN Capture Volume"</span>, RX_DVC_<span class="hl-number">1</span>_<span class="hl-number">2</span>_CTRL_REG,
RX_DVC1_GAIN, RX_DVC2_GAIN,
<span class="hl-number">0xFF</span>, <span class="hl-number">0</span>, aic_codec_dvc_scale),
SOC_DOUBLE_TLV(<span class="hl-string">"AUDIO Playback Volume"</span>, TX_DVC_<span class="hl-number">3</span>_<span class="hl-number">4</span>_CTRL_REG,
TX_DVC3_GAIN, TX_DVC4_GAIN,
<span class="hl-number">0xFF</span>, <span class="hl-number">0</span>, aic_codec_dvc_scale),
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
SOC_SINGLE_TLV(<span class="hl-string">"ADC Capture Volume"</span>, ADC_DVC0_CTRL_REG,
ADC_DVC0_CTRL_DVC0_GAIN,
<span class="hl-number">0xFF</span>, <span class="hl-number">0</span>, aic_codec_dvc_scale),
SOC_SINGLE_TLV(<span class="hl-string">"PGA Gain"</span>, ADC_CTL2_REG, ADC_CTL2_PGA_GAIN_SEL,
<span class="hl-number">0xF</span>, <span class="hl-number">0</span>, aic_pga_scale),
#endif
SOC_SINGLE_TLV(<span class="hl-string">"MIX1AUDL Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER1_AUDOUTL_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX1AUDR Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER1_AUDOUTR_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX1DMICL Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER1_DMICOUTL_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX1DMICR Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER1_DMICOUTR_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
SOC_SINGLE_TLV(<span class="hl-string">"MIX1ADC Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER1_ADCOUT_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
#endif
SOC_SINGLE_TLV(<span class="hl-string">"MIX0AUDL Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER0_AUDOUTL_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX0AUDR Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER0_AUDOUTR_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX0DMICL Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER0_DMICOUTL_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
SOC_SINGLE_TLV(<span class="hl-string">"MIX0DMICR Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER0_DMICOUTR_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
SOC_SINGLE_TLV(<span class="hl-string">"MIX0ADC Playback Gain"</span>, TX_MIXER_CTRL_REG,
TX_MIXER0_ADCOUT_GAIN, <span class="hl-number">1</span>,
<span class="hl-number">1</span>, aic_mixer_source_gain_scale),
#endif
SOC_ENUM(<span class="hl-string">"Data Swap Switch"</span>, dmicif_data_enum),
SOC_ENUM(<span class="hl-string">"RXFIFO Delay Time"</span>, dmic_rx_dlt_length_enum),
SOC_ENUM(<span class="hl-string">"RXFIFO Dealy Switch"</span>, dmic_rx_dlt_en_enum),
SOC_ENUM(<span class="hl-string">"AMIC bias voltage level"</span>, mic_bias_voltage_enum),
SOC_ENUM(<span class="hl-string">"PWM0 mode select"</span>, pwm0_mode_enum),
SOC_ENUM(<span class="hl-string">"PWM1 mode select"</span>, pwm1_mode_enum),
SOC_ENUM(<span class="hl-string">"MIXER0 swicth"</span>, mixer0_enable_enum),
SOC_ENUM(<span class="hl-string">"MIXER1 swicth"</span>, mixer1_enable_enum),
};</code></pre></div>
</li>
<li class="- topic/li li" data-ofbid="d57970e184__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e186__20250123155202">将定义的音频控件数组赋值给 codec 的 component
driver<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_zhr_41n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_zhr_41n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_component_driver aic_codec_component = {
.controls = aic_codec_controls,
.num_controls = ARRAY_SIZE(aic_codec_controls),
.dapm_widgets = aic_codec_dapm_widgets,
.num_dapm_widgets = ARRAY_SIZE(aic_codec_dapm_widgets),
.dapm_routes = aic_codec_dapm_route,
.num_dapm_routes = ARRAY_SIZE(aic_codec_dapm_route),
.idle_bias_on = <span class="hl-number">1</span>,
.use_pmdown_time = <span class="hl-number">1</span>,
.endianness = <span class="hl-number">1</span>,
.non_legacy_dai_naming = <span class="hl-number">1</span>,
};
</code></pre></div>
</li>
<li class="- topic/li li" data-ofbid="d57970e192__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e194__20250123155202">调用 component 完成音频控件的注册。</p>
</li>
</ol>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_bw1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_bw1_h1n_d1c"><h2 class="- topic/title title sectiontitle">dmaengine_pcm 注册</h2>
<p class="- topic/p p" data-ofbid="d57970e205__20250123155202">在 d211 中，capture 端新增了 amic 通路。在 DMA 传输时，amic 和 dmic 使用不同的 id。所以为了区分不同的 id，在 DTS 中新增了一个结点，用于注册一个新的 pcm 设备。并新增 c 文件，在该文件中实现对新的 pcm 设备的注册。</p>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_cw1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_cw1_h1n_d1c"><h2 class="- topic/title title sectiontitle">period-bytes 对齐</h2>
<div class="- topic/p p" data-ofbid="d57970e215__20250123155202">在使用 DMA 传输音频数据时，DMA 要求每次传输的数据长度必须 128bytes/8bytes 对齐。在 ALSA 框架下，音频数据以 period 为周期调用 DMA 传输，每次传输的数据长度为 bytes。所以，必须满足 bytes 按照 128bytes/8bytes 对齐。ALSA 中提供了相应的 API 接口(snd_pcm_hw_constraint_step)来满足这一需求。<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_vyh_r1n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_vyh_r1n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">int</strong> aic_codec_startup(<strong class="hl-keyword">struct</strong> snd_pcm_substream *substream,
<strong class="hl-keyword">struct</strong> snd_soc_dai *dai)
{
<strong class="hl-keyword">int</strong> ret;
<em class="hl-comment">/* Make sure that the period bytes are 8/128 bytes aligned according to
* the DMA transfer requested.
*/</em>
#ifdef CONFIG_SND_SOC_AIC_CODEC_V1
ret = snd_pcm_hw_constraint_step(substream-&gt;runtime, <span class="hl-number">0</span>,
SNDRV_PCM_HW_PARAM_PERIOD_BYTES, <span class="hl-number">8</span>);
<strong class="hl-keyword">if</strong> (ret &lt; <span class="hl-number">0</span>) {
dev_err(dai-&gt;dev, <span class="hl-string">"Could not apply period step: %d\n"</span>, ret);
<strong class="hl-keyword">return</strong> ret;
}
ret = snd_pcm_hw_constraint_step(substream-&gt;runtime, <span class="hl-number">0</span>,
SNDRV_PCM_HW_PARAM_BUFFER_BYTES, <span class="hl-number">8</span>);
<strong class="hl-keyword">if</strong> (ret &lt; <span class="hl-number">0</span>) {
dev_err(dai-&gt;dev, <span class="hl-string">"Could not apply buffer step: %d\n"</span>, ret);
<strong class="hl-keyword">return</strong> ret;
}
#<strong class="hl-keyword">else</strong>
ret = snd_pcm_hw_constraint_step(substream-&gt;runtime, <span class="hl-number">0</span>,
SNDRV_PCM_HW_PARAM_PERIOD_BYTES, <span class="hl-number">128</span>);
<strong class="hl-keyword">if</strong> (ret &lt; <span class="hl-number">0</span>) {
dev_err(dai-&gt;dev, <span class="hl-string">"Could not apply period step: %d\n"</span>, ret);
<strong class="hl-keyword">return</strong> ret;
}
ret = snd_pcm_hw_constraint_step(substream-&gt;runtime, <span class="hl-number">0</span>,
SNDRV_PCM_HW_PARAM_BUFFER_BYTES, <span class="hl-number">128</span>);
<strong class="hl-keyword">if</strong> (ret &lt; <span class="hl-number">0</span>) {
dev_err(dai-&gt;dev, <span class="hl-string">"Could not apply buffer step: %d\n"</span>, ret);
<strong class="hl-keyword">return</strong> ret;
}
#endif
<strong class="hl-keyword">return</strong> ret;
}</code></pre></div>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_ew1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_ew1_h1n_d1c"><h2 class="- topic/title title sectiontitle">pop 音消除</h2>
<p class="- topic/p p" data-ofbid="d57970e226__20250123155202">在音频的驱动设计中，播放上下电时的 pop 音是经常遇到的一个问题。pop 音产生的主要原因如下：</p>
<ol class="- topic/ol ol" id="audio_codec_key_procedures__ol_fw1_h1n_d1c" data-ofbid="audio_codec_key_procedures__ol_fw1_h1n_d1c">
<li class="- topic/li li" data-ofbid="d57970e231__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e233__20250123155202">音频通路中的控件还未全部闭合时，功放却已处于工作状态。此时当其它控件闭合形成播放通路时，通路中电流的变化经功放放大，形成 pop 音。</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e237__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e239__20250123155202">在正常播放过程中，播放不同采样率的音频文件时，导致 audio 频率切换，此时也容易产生 pop 音。例如，当前播放的是 48K 采样率的音频文件，下一个音频文件的采样率是 22.05K，需要切换 audio 模块的工作频率，切换频率时有可能产生 pop 音。</p>
</li>
</ol>
<p class="- topic/p p" data-ofbid="d57970e244__20250123155202">基于以上原因，为了消除 pop 音的问题，audio 的驱动设计中做了以下几点设计：</p>
<ol class="- topic/ol ol" id="audio_codec_key_procedures__ol_gw1_h1n_d1c" data-ofbid="audio_codec_key_procedures__ol_gw1_h1n_d1c">
<li class="- topic/li li" data-ofbid="d57970e249__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e251__20250123155202">在 DTS 中添加 gpio 引脚，用于控制功放的使能和禁用<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_av2_s1n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_av2_s1n_d1c"><code>&amp;codec {
pinctrl-names = <span class="hl-string">"default"</span>;
pinctrl-<span class="hl-number">0</span> = &lt;&amp;amic_pins&gt;, &lt;&amp;dmic_pins_a&gt;, &lt;&amp;spk_pins_b&gt;;
pa-gpios = &lt;&amp;gpio_f <span class="hl-number">13</span> GPIO_ACTIVE_LOW&gt;;
status = <span class="hl-string">"okay"</span>;
};</code></pre></div>
</li>
<li class="- topic/li li" data-ofbid="d57970e257__20250123155202">
<div class="- topic/p p" data-ofbid="d57970e259__20250123155202">调整音频通路中的上下电顺序，确保通路最后才使能功放。ALSA 中提供的 widget 宏已经对上下电做好了排序，调用相应的宏定义 widget 即可。<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="audio_codec_key_procedures__codeblock_cpr_s1n_d1c" data-ofbid="audio_codec_key_procedures__codeblock_cpr_s1n_d1c"><code><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_dapm_widget aic_codec_card_dapm_widgets[] = {
SND_SOC_DAPM_SPK(<span class="hl-string">"Speaker"</span>, aic_codec_spk_event),
};
<strong class="hl-keyword">static</strong> <strong class="hl-keyword">int</strong> aic_codec_spk_event(<strong class="hl-keyword">struct</strong> snd_soc_dapm_widget *w,
<strong class="hl-keyword">struct</strong> snd_kcontrol *k, <strong class="hl-keyword">int</strong> event)
{
<strong class="hl-keyword">if</strong> (SND_SOC_DAPM_EVENT_ON(event) &amp;&amp; !IS_ERR_OR_NULL(gpiod_pa))
gpiod_set_value(gpiod_pa, <span class="hl-number">1</span>);
<strong class="hl-keyword">else</strong> <strong class="hl-keyword">if</strong> (SND_SOC_DAPM_EVENT_OFF(event) &amp;&amp; !IS_ERR_OR_NULL(gpiod_pa))
gpiod_set_value(gpiod_pa, <span class="hl-number">0</span>);
msleep(<span class="hl-number">100</span>);
<strong class="hl-keyword">return</strong> <span class="hl-number">0</span>;
}
<strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> snd_soc_dapm_widget aic_codec_dapm_widgets[] = {
...
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"TX GLBEN"</span>, GLOBE_CTL_REG, GLOBE_TX_GLBEN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
SND_SOC_DAPM_SUPPLY(<span class="hl-string">"RX GLBEN"</span>, GLOBE_CTL_REG, GLOBE_RX_GLBEN,
<span class="hl-number">0</span>, NULL, <span class="hl-number">0</span>),
...
}</code></pre></div>
<p class="- topic/p p" data-ofbid="d57970e264__20250123155202">在使能和禁用功放的 widget 时，通过 event 回调函数使能和禁用功放。soc-dapm.c 文件的 seq 和 dapm_down_seq 数组定义了各个 widget 的上下电顺序。而由 SPK 宏定义的功放 widget，处于上电时最后上电，掉电时较早掉电的位置。将 TX 和 RX 的全局使能加入 widget 链路，确保先于功放使能。</p>
</li>
<li class="- topic/li li" data-ofbid="d57970e268__20250123155202">
<p class="- topic/p p" data-ofbid="d57970e270__20250123155202">audio 需要调整频率时，先关闭功放，频率调整后，再将功放恢复到频率调整前的状态。</p>
</li>
</ol>
</section>
<section class="- topic/section section" id="audio_codec_key_procedures__section_lw1_h1n_d1c" data-ofbid="audio_codec_key_procedures__section_lw1_h1n_d1c"><h2 class="- topic/title title sectiontitle">创建声卡</h2>
<p class="- topic/p p" data-ofbid="d57970e281__20250123155202">创建声卡的一个关键步骤是实现 driver 和 codec driver 的耦合，ALSA 框架中，实现二者耦合是通过 link 实现的。在调用 component 时，会把相应的 platform 和 codec 所对应的 component 注册到链表中。在注册声卡时，会根据 link 中定义的 codecs-&gt;dai_name 和 cpus-&gt;dai_name 进行查找，如果在链表中可以查找到相应的 dai，则耦合成功，否则会耦合失败。</p>
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<div class=" wh_topic_toc "><div class="wh_topic_label">在本页上</div><ul><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_hv1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_hv1_h1n_d1c">初始化流程</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_jv1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_jv1_h1n_d1c">音频通路设置</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_nv1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_nv1_h1n_d1c">音频通路的注册</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_vv1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_vv1_h1n_d1c">音频控件设置</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_bw1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_bw1_h1n_d1c">dmaengine_pcm 注册</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_cw1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_cw1_h1n_d1c">period-bytes 对齐</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_ew1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_ew1_h1n_d1c">pop 音消除</a></div></li><li class="section-item"><div class="section-title"><a href="#audio_codec_key_procedures__section_lw1_h1n_d1c" data-tocid="audio_codec_key_procedures__section_lw1_h1n_d1c">创建声卡</a></div></li></ul></div>
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