[BUG] CS8409 codec detected but non-functional due to missing UCM (iMac18,3)

[BUG] CS8409 codec detected but non-functional due to missing UCM (iMac18,3)

[Marek Havlík]

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Hello ALSA developers,


I’m reporting an issue affecting Apple iMac 18,3 (27", 2017) running Ubuntu 24.04 LTS. The Cirrus Logic CS8409 codec is detected correctly by ALSA, and the `snd_hda_codec_cs8409` module loads without errors. However, due to the absence of a UCM profile, the audio subsystem remains non-functional — no outputs, no mixer controls, and PipeWire ignores the device.


Diagnostics confirm:
- Codec is detected and initialized (NID 0x24, 0x25 for speakers; NID 0x45 for internal mic)
- ALSA registers the device as card0
- HDMI outputs (card1) work, but CS8409 remains unusable
- PipeWire does not expose CS8409 as a usable device


alsa-info output:  
http://alsa-project.org/db/?f=45ed57a6e0a42cb82202b8429318197a073fc0bf  
→ This confirms that the CS8409 codec is detected and initialized, but no output devices or mixer controls are available.


I’ve also attached a ZIP archive (`imac18-3_diagnostics.zip`) containing original BootCamp hardware documentation extracted from macOS Ventura. It includes component identifiers for:
- Cirrus Logic CS8409 and CS42L83
- AMDGPU (graphics with HDMI audio)
- Apple internal webcam


This documentation may assist in developing accurate UCM profiles, initialization routines, or improving hardware detection logic.


Full bug report with diagnostics and testing history:  
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2119402


I’m happy to assist with testing, validation, or UCM development. I have access to the physical hardware and am willing to help if there’s interest in resolving this.


Thank you for your work and consideration.


Best regards,  
Marek Havlík (mahav-t)


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