# Configure device node in ALSA interface

Source: [https://docs.qualcomm.com/doc/80-88500-3/topic/24_Configure_device_node_in_ALSA_interface.html](https://docs.qualcomm.com/doc/80-88500-3/topic/24_Configure_device_node_in_ALSA_interface.html)

The QRB5165 device has implemented ALSA drivers to provide audio hardware capability to the user space. During board bootup, the `init_audio.service` system service brings up the ALSA module.

After bootup, the following device nodes are under the /dev/snd directory.

Table : Device nodes in ALSA modules

| Device node name | Description |
| --- | --- |
| `/dev/snd/comprC0Dxx` | Compressed offload playback or capture.<br><br><br>              <ul class="ul" id="Configure_device_node_in_ALSA_interface_24__ul_vxx_2px_rxb"><br>                <li class="li">For offload playback, the QRB5165 device supports AAC and MP3 format</li><br><br>                <li class="li">For offload capture, the QRB5165 device supports AAC format</li><br><br>              </ul> |
| `/dev/snd/controlC0` | ALSA utility tools to access this node for audio card information and mixer controls.<br><br><br>              <br>For example, the command `amixer contents` can get the mixer settings through this node. |
| `/dev/snd/hwC0Dxxx` | Hardware-dependent nodes for audio back end.<br><br><br>              <br>The QRB5165 device loads calibration data into the audio device through these nodes. |
| `/dev/snd/pcmC0Dxxc` | PCM data capture |
| `/dev/snd/pcmC0Dxxp` | PCM data playback |

The partial mappings between device nodes and DAI name are shown in the following table. The
      DAI name is in the mixer\_paths\_iot.xml file.

Table : Device node and mixer control mapping

| Device node name | DAI name | Path name | Mixer controls |
| --- | --- | --- | --- |
| `pcmC0D0c` | MultiMedia1 | `audio-record` | <path name="audio-record"> <ctl name="MultiMedia1 Mixer TX_CDC_DMA_TX_3" value="1" /> </path>Copy to clipboard |
| `pcmC0D0c` | MultiMedia1 | `audio-record hdmi-in` | <path name="audio-record hdmi-in"> <ctl name="MultiMedia1 Mixer QUAT_MI2S_TX" value="1" /> </path> Copy to clipboard |
| `pcmC0D7c<br>              ``pcmC0D7p` | MultiMedia4 | `compress-offload-playback` | <path name="compress-offload-playback"> <ctl name="WSA_CDC_DMA_RX_0 Audio Mixer MultiMedia4" value="1" /> </path> Copy to clipboard |
| `pcmC0D9c<br>              ``pcmC0D9p` | MultiMedia5 | `low-latency-playback` | <path name="low-latency-playback"> <ctl name="WSA_CDC_DMA_RX_0 Audio Mixer MultiMedia5" value="1" /> </path> Copy to clipboard |

**Parent Topic:** [Configure audio settings](https://docs.qualcomm.com/doc/80-88500-3/topic/18_Configure_audio_settings.html)

Last Published: Sep 26, 2023

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