CS8409 Audio DKMS (Debian/Ubuntu on Intel Macs)

This repository provides a DKMS-based audio enablement for Intel Macs (iMac, MacBook, Mac mini, iMac Pro, Mac Pro) that use Cirrus Logic CS8409 HDA audio with a CS42L42 companion codec — the common setup on many T2-era Macs (2018–2020) running Linux (Debian/Ubuntu). On these machines, users frequently hit “no sound” because the Linux kernel may lack model-specific initialization and resume quirks out of the box. This project bundles kernel-compatible driver sources and installs them via DKMS, plus an optional resume workaround, to make audio work reliably across kernel updates and sleep/wake cycles.

• Why this repo? It is a consolidation and forward-evolution of existing community solutions for CS8409/CS42L42 on T2 Macs. It integrates community driver work and adds small glue fixes, wrapped as a DKMS module so that audio keeps working after kernel updates — and includes a suspend/resume fix for the notorious “no audio after suspend” issue.
• What you get
  • Sound out of the box on supported Macs (speakers/headphones, mic, HDA controls).
  • DKMS auto-rebuild across kernel upgrades (solves “no sound after kernel update”).
  • Suspend/resume fix (“no sound after suspend”), via a minimal systemd sleep hook and recommended runtime settings for T2 hardware.
  • A clean uninstall path.

This repository ships no proprietary firmware. It provides open driver sources for the HDA codec path and integrates them via DKMS. It also applies optional configuration to improve suspend/resume on T2-era Macs.

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Supported hardware (examples)

Intel Macs with CS8409 + CS42L42 audio path, typically:

• iMac 2019/2020 (iMac19,1, iMac19,2, iMac20,1, iMac20,2)
• MacBook Pro 2018–2020 (MacBookPro15,x, MacBookPro16,x)
• Mac mini 2018 (Macmini8,1)
• iMac Pro (iMacPro1,1)

The installer auto-detects supported hardware. If a similar model isn’t recognized, the module may refuse to load or create incomplete nodes — please open an issue with dmesg and alsactl info output.

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What the installer actually does

1. Sanity checks & prerequisites

   • Ensures root, verifies required tools and kernel headers are present.
   • Detects the running kernel (and any installed kernels) to determine DKMS build targets.
     Note: This repo does not check or update your kernel (unlike the Wi-Fi wrapper).

2. Build & install via DKMS

   • Registers the module (e.g. snd-hda-codec-cs8409) with DKMS.
   • Builds against your current headers and installs it for all installed kernels (or specific targets you select via flags below).
   • Ensures automatic rebuild on future kernel updates.

3. Apply runtime settings for T2 stability

   • Writes recommended kernel parameters for T2 audio:
     snd-intel-dspcfg.dsp_driver=1 mem_sleep_default=s2idle
   • By default, installs a minimal systemd sleep hook (xHCI / s2idle workaround) to avoid “no sound after suspend” on affected models. If you run with --no-suspend-patch, the installer keeps snd-intel-dspcfg.dsp_driver=1 for audio but skips the mem_sleep_default=s2idle flag and does not install the hook.

   Installs (when enabled):

   • helper script: /usr/lib/systemd/system-sleep/98-xhci-s2idle-unbind.sh (or /lib/systemd/system-sleep/… on non-usrmerge)
   • config file: /etc/default/xhci-s2idle

4. Uninstall helpers

   • Provides steps to unregister the DKMS package and revert optional settings (sleep hook + config).

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Requirements

• Debian 12/13 or Ubuntu 22.04/24.04 (or newer)
• Kernel headers for your running kernel (e.g. linux-headers-$(uname -r))
• Tools: git, build-essential (or base-devel equivalent), wget, dkms, kmod, rsync, patch, pciutils, alsa-utils, pavucontrol, pulseaudio-utils

Install helpers (Debian/Ubuntu):

sudo apt update
sudo apt install -y git build-essential wget dkms kmod rsync patch pciutils alsa-utils pavucontrol pulseaudio-utils pkg-config alsa-tools linux-headers-$(uname -r)

Secure Boot (Debian/Ubuntu): If Secure Boot is enabled, unsigned DKMS modules won’t load. Either disable Secure Boot in firmware, or enroll a Machine Owner Key (MOK) and sign the DKMS module (Ubuntu typically prompts for MOK enrollment during dkms builds).

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Quick start

git clone https://github.com/frogro/cs8409-audio-dkms
cd cs8409-audio-dkms
sudo chmod +x install.sh
sudo ./install.sh

After installation, you should see devices under aplay -l. If audio is muted, open alsamixer or pavucontrol and check the output path.

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Command-line options

These options select which kernel versions the DKMS module is built for and how the install behaves.
They do not check or upgrade your kernel.

Usage: sudo ./install.sh [--kver <ver>]... [--all-installed] [--no-reload] [--no-suspend-patch]
Default: build for the running kernel and apply suspend patch

• --kver <ver> — build for a specific kernel version (can be used multiple times).
• --all-installed — build for all installed kernels on this system.
• --no-reload — do not reload the driver stack immediately after install.
• --no-suspend-patch — keep snd-intel-dspcfg.dsp_driver=1 for audio, but skip mem_sleep_default=s2idle and the xHCI sleep hook.

When to use these options (practical rationale)

• --kver <ver>: build for a non-running kernel (e.g. you installed headers for a new kernel but haven’t rebooted yet; building in chroot/CI; testing another ABI).
• --all-installed: pre-build for every kernel already present under /lib/modules/… so audio works immediately no matter which installed kernel you boot next (useful if multiple kernels are installed, e.g. generic + HWE). DKMS will also build automatically on future kernel installs; this just catches up for kernels already on disk.
• --no-reload: skip immediate module reload if you prefer to reboot later or avoid disrupting active audio sessions. It does not replace a reboot; it simply defers activation until the next boot or manual reload.

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Installer mapping / File layout

• DKMS name & version: read from dkms.conf (PACKAGE_NAME, PACKAGE_VERSION) — typically snd-hda-codec-cs8409 and a repo version.
  DKMS source dir: /usr/src/<DKMS_NAME>-<DKMS_VER>/
• Built module install path (per kernel): standard DKMS location under
  /lib/modules/<kver>/updates/dkms/
• Sleep hook script (if enabled):
  /usr/lib/systemd/system-sleep/98-xhci-s2idle-unbind.sh (or /lib/systemd/system-sleep/… on non-usrmerge systems)
• Sleep hook config:
  /etc/default/xhci-s2idle
• GRUB config touched:
  /etc/default/grub (parameters: snd-intel-dspcfg.dsp_driver=1 mem_sleep_default=s2idle → apply with update-grub)
• Modules (re)loaded by the installer:
  snd_hda_intel, snd_hda_codec, snd_hda_codec_cs8409

Note: Some distros may use /lib/systemd/system-sleep/ instead of /usr/lib/systemd/system-sleep/. The installer chooses a suitable directory automatically.

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Uninstall / Revert

# Hard-stop user-space audio
systemctl --user stop wireplumber pipewire pipewire-pulse 2>/dev/null || true
pkill -x wireplumber pipewire pipewire-pulse 2>/dev/null || true

# Check who is holding /dev/snd/*
fuser -v /dev/snd/* 2>/dev/null || true

# Unbind HDA PCI functions (PCH + dGPU HDMI audio; ignore if not present)
for bdf in 0000:00:1f.3 0000:01:00.1; do
  if [ -e /sys/bus/pci/devices/$bdf/driver ]; then
    echo $bdf | sudo tee /sys/bus/pci/devices/$bdf/driver/unbind
  fi
done

# Unload modules (order matters; ignore errors)
sudo modprobe -r snd_hda_codec_cs8409 snd_hda_codec_hdmi snd_hda_codec snd_hda_intel || true

# Remove the DKMS package
sudo dkms remove -m snd-hda-codec-cs8409 -v 1.0+dkms --all

# Remove hook + config
sudo rm -f /usr/lib/systemd/system-sleep/98-xhci-s2idle-unbind.sh /lib/systemd/system-sleep/98-xhci-s2idle-unbind.sh
sudo rm -f /etc/default/xhci-s2idle

# Refresh module dependency maps (initramfs update not needed here)
sudo depmod -a

Revert the recommended GRUB kernel parameters (optional)

If you previously allowed the installer to add snd-intel-dspcfg.dsp_driver=1 and mem_sleep_default=s2idle, you can remove them:

sudo cp /etc/default/grub /etc/default/grub.bak.$(date +%F)
sudo sed -i 's/ *snd-intel-dspcfg.dsp_driver=1//; s/ *mem_sleep_default=s2idle//' /etc/default/grub
sudo update-grub

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Troubleshooting

• No devices in aplay -l

  • Make sure headers match your kernel: dpkg -l | grep linux-headers vs uname -r.
  • Check module: lsmod | egrep 'cs8409|snd_hda_intel'.
  • Look for errors: dmesg | egrep -i 'cs8409|cs42l42|hda|firmware' | tail -n 200.

• No sound after suspend

  • Ensure the xHCI s2idle hook is enabled and the system uses s2idle.
  • Reboot after enabling.

• Module builds but does not load (Secure Boot)

  • Sign the module via MOK or temporarily disable Secure Boot.

• Regression after kernel upgrade

  • Verify DKMS rebuilt: dkms status. Re-run sudo ./install.sh if needed.

When reporting issues, include:

uname -r
lsmod | egrep 'cs8409|snd_hda_intel'
dmesg | egrep -i 'cs8409|cs42l42|hda|xHCI|suspend' | tail -n 200
aplay -l
sudo alsactl info

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Sources integrated / Credits

This project builds on and integrates work from:

• The Linux kernel ALSA HDA subsystem (including snd-hda-codec-cs8409 and related Cirrus codec pieces).
• Community driver work by egorenar and contributors: https://github.com/egorenar/snd-hda-codec-cs8409 (adapted/integrated here).
  If you authored a specific change we integrated and want a named credit, open an issue/PR with the source URL and your preferred credit line — we’ll add it under Sources integrated / Credits.

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Security and integrity

This repo provides open source code only. It does not include proprietary firmware. Sources are compiled locally against your headers via DKMS.

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License

This repository contains components under two licenses:

• Kernel-adjacent code (driver code and any sources that compile into a kernel module, typically under src/): GPL-2.0-only (Linux kernel compatibility and GPL-only symbols).
• Build/packaging scripts and docs (e.g. install.sh and this README): MIT License.

See LICENSE for the full texts and which paths each license applies to.

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Contributing

Issues and PRs are welcome. Please include logs (see Troubleshooting) and your distro/kernel details. Contributions should keep DKMS compatibility and resume reliability in mind.