Hi, Kevin Becker (kevinbecker) Thanks for your suggestion. I followed the instructions provided at Ubuntu's kernel lifecycle page and successfully upgraded to the latest HWE kernel β 6.14.0-27 β on Ubuntu 24.04.3 LTS.
Unfortunately, the issue persists. The snd_hda_intel module loads correctly, and ALSA detects the codec (Realtek ALC1220), but there is still no UCM profile available for this device. As a result, the system remains without functional audio output. Diagnostic Report: CS8409 on iMac18,3 running Ubuntu 24.04.3 (kernel 6.14.0-27) π₯οΈ Hardware Model: iMac18,3 (Apple) Audio chip: Cirrus Logic CS8409 GPU: AMD Radeon (with HDMI audio) π§ͺ Test Environment Ubuntu Live 24.04.3 Kernel: 6.14.0-27-generic Wayland session PipeWire active π¦ Driver Status The snd_hda_codec_cs8409 module loads correctly: bash lsmod | grep cs8409 dmesg confirms detection and autoconfiguration: text snd_hda_codec_cs8409 hdaudioC0D0: autoconfig for CS8409: line_outs=2 (0x24/0x25) type:speaker ... Internal Mic=0x45, Mic=0x3c π Issue ALSA registers card0 (CS8409), but: No output devices No mixer controls GUI shows only HDMI outputs (card1) PipeWire does not recognize card0 as a usable device alsa-info.sh output: http://alsa- project.org/db/?f=45ed57a6e0a42cb82202b8429318197a073fc0bf π Likely Cause Missing UCM profile for CS8409, so ALSA doesn't know how to interact with the hardware. The module works, but without defined outputs/mixers, it's non-functional. β Verified Module loads ALSA registers it dmesg shows correct detection PipeWire is running but ignores card0 HDMI outputs are functional π‘ Suggested Solution Create and add a UCM profile for CS8409 (e.g., ucm2/CS8409/HiFi.conf) Define basic mixer controls and outputs Verify compatibility with PipeWire -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2119402 Title: )Persistent driver issues on iMac 18,3 (27", 2017) Status in linux package in Ubuntu: Incomplete Bug description: Summary: After long-term testing of Ubuntu 24.04.2 LTS on the Apple iMac 18,3 (27", 2017), Iβve concluded that the system contains all necessary drivers β located in the kernel and in packages like linux- modules-extra β but their behavior is unpredictable. Ubuntu often fails to load, assign, or correctly activate them during installation. There are ongoing issues affecting sound, graphics drivers, internal microphone, and webcam functionality. π Observed issues: Audio β Cirrus Logic CS8409 / CS42L83 The snd-hda-codec-cs8409 module is available, but not properly initialized. The system shows βDummy Outputβ and audio doesnβt work without manual patching. Internal microphone (NID 0x45) is detected but inactive. Missing alsa-ucm-conf profile β no devices or input streams shown in GUI. Graphics β AMD Radeon (AMDGPU) On installation, the system loads Mesa fallback driver β incorrect resolution and audio instability. Installing AMDGPU driver 25.10.1 resolved both resolution and audio subsystem interaction issues. Webcam (Apple internal) Camera launches via cheese, but turns off abruptly during recording. Likely related to power delivery, ACPI events, or missing initialization routines. π§ͺ Diagnostics & insights: Upstream kernel 6.16-rc6 contains working DMIC initialization for microphone (patch_cs8409.c). Ubuntu kernel 6.11 includes the CS8409 module, but lacks full microphone functionality. Drivers exist, but: Are not loaded automatically during installation. Are not assigned correctly to hardware. Do not activate input/output devices without manual effort. π Attached information: Diagnostic logs from alsa-info.sh, dmesg, arecord, pw-dump Technical analysis of upstream kernel code (DMIC logic β NID 0x45) Attached .txt file containing hardware documentation extracted from Apple BootCamp: Retrieved from system path: marek- havlik@mahav:~/Plocha/WindowsSupport$ ls '$WinPEDriver$' BootCamp The file includes component identifiers (CS8409, CS42L83, AMDGPU, webcam) helpful for developing UCM profiles and driver assignments. π οΈ Suggestions to the development team: Include a proper UCM profile for CS8409 / CS42L83 in alsa-ucm-conf Backport DMIC activation patch from kernel 6.16 to Ubuntu 6.11+ Improve hardware detection logic to: Load modules without manual intervention Automatically match drivers during Ubuntu installation Prefer AMDGPU over Mesa fallback when Apple hardware is detected Investigate webcam and microphone behavior β possibly caused by ACPI, UVC or missing init triggers Note: Due to recurring issues, I no longer actively use Ubuntu on this system. However, I am happy to assist with testing, validating patches, or helping with a DKMS implementation. I have access to the real hardware (iMac18,3) as well as the original BootCamp documentation from macOS. Thank you for your work β I hope these insights help improve Apple hardware support on Ubuntu. β Marek (mahav-t) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2119402/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
