Asahi Linux (fairydust with DP/HDMI Audio & 120Hz Fixes)

This fork contains fixes for Apple Silicon (tested on Mac mini M1 / j274) to enable stable 4K @ 120Hz video and DP/HDMI audio over USB-C (ATC PHYs) and the built-in HDMI port.

Problems Solved

Upstream appledrm.hdmi_audio=1 was experimental and suffered from several issues across standby, hotplug, and modesets:

1. AFK Slot Leak: av_audiosrv_teardown() did not clear service->enabled = false, exhausting the 16 AFK endpoint channel slots after repeated power cycles.
2. WirePlumber Probe Race / Standby Profile Loss: dcp_pcm_open() returned -ENXIO when the screen was disconnected/sleeping, causing WirePlumber to permanently drop the stereo profile on boot or restart.
3. Standby Reconnect Recovery: When the display woke up, the stream stalled because open_cookie was out of sync. Replaced SNDRV_PCM_STATE_DISCONNECTED with snd_pcm_stop_xrun() and synced cookies on prepare().
4. SIO DMA Descriptors & Period Limits: Fixed descriptor bitmap size (devm_bitmap_zalloc) and capped ALSA periods_max at 32 to prevent -ENOMEM loops under PipeWire.
5. Modeset Order: Audio service initialization is deferred until after iomfb_modeset() to prevent display pipeline failures on ATC PHYs.
6. Service Teardown, PM Balance & Disconnected State: Guarded afk_service_call() and dcp_audiosrv_* against NULL service pointers during display standby, balanced runtime PM get/put via link_started, and returned -ENODEV on disconnected prepare/start to eliminate runaway PipeWire CPU spin loops.

Branches

• fairydust: Rebased on latest Asahi upstream (asahi-7.1.12-1 / kernel 7.1.12).
• fairydust-7.1.6: Stable tree matching Fedora Asahi Remix 7.1.6 kernel.

Building the Kernel Module

To compile just the appledrm module:

make -j$(nproc) M=drivers/gpu/drm/apple

Patches

All patches and cover letters are also exported as git format-patches in asahi-patches/.