This repository contains packages for Debian and Arch Linux that installs the Linux kernel 4.4 with a set of patches that enable sound support as well as keyboard and screen brightness control. The Linux kernel 4.4 already has built-in support for the touchpad making the Pixel 2 fully supported with this kernel tree.

The repository also contains the complete source for the patched kernel tree so that it can be built and installed on other Linux distributions.

The set of scripts used to create the patched linux kernel source is also included. These scripts diff the ChromiumOS 3.14 tree (that's the version used to create the Pixel 2 ChromeOS kernel) with the 4.4 tree and apply a small set of custom changes necessary to make the code compatible.

The provided kernel config is also somewhat optimized for the Pixel 2.

Current kernel version: 4.4.1

The easiest way to get going is to install the packages if you are running Ubuntu, Debian or Arch Linux.

$ git clone https://github.com/raphael/linux-samus
$ cd linux-samus/build/debian
$ sudo dpkg -i *.deb

Install from the AUR:

yaourt -S linux-samus4

The entire kernel patched tree is located under build/linux, compile and install using the usual instructions for installing kernels. For example:

$ git clone https://github.com/raphael/linux-samus
$ cd linux-samus/build/linux
$ make nconfig
$ make -j4
$ sudo make modules_install
$ sudo make install

NOTE the steps above are just the standard kernel build steps and may differ depending on your distro/setup. In particular the default kernel makefile assumes LILO is being used. Follow the instructions specific to your distribution for installing kernels from source.

Once installed reboot and load the kernel.

To enable sound run the sound.sh script:

$ cd linux-samus/scripts/setup/sound
$ ./sound.sh

NOTE this scripts makes a number of assumptions on your system (e.g. alsaucm and amixer are both installed and the file /etc/pulse/default.pa contains a line to load the modules using udev). If the setup script fails please see below "Enabling sound step-by-step".

To set the default sink from the laptop speakers when logged in, modify the users pulseaudio config with:

pacmd set-default-sink 1

the following commands will control sound:

pactl set-sink-mute 1 toggle
pactl set-sink-volume 1 -2%
pactl set-sink-volume 1 +2%

Since Linux 4.3 the Atmel chip needs to be reconfigured to guarantee that the touchpad works. See issue #73 for details. The linux-samus/scripts/setup/touchpad directory contains a script that does the reconfig:

$ cd linux-samus/scripts/setup/touchpad
$ ./enable-atmel.sh

This is only needed to be run once.

To enable X11 acceleration run the xaccel.sh script:

$ cd linux-samus/scripts/setup/xorg
$ ./xaccel.sh

The script script/setup/brightness/brightness can be used to control the brightness level.

$ cd scripts/setup/brightness
$ ./brightness --help
Increase or decrease screen brighness
Usage: brightness --increase | --decrease

Bind the F6 key to brightness --decrease and the F7 key to brightness --increase for an almost native experience... (assuming the scripts are in your path).

Similarly the script script/setup/brightness/keyboard_led can be used to control the keyboard backlight, bind the ALT-F6 key to keyboard_led --decrease and ALT-F7 to keyboard_led --increase.

Both these scripts require write access to files living under /sys which get mounted read-only for non-root users on boot by default. If your system uses systemd (e.g. ArchLinux) then the file script/setup/brightness/enable-brightness.service contains the definition for a systemd service that makes the files above writable to non-root user. Run systemctl enable enable-brightness.service for the service to run on boot.

./setup.systemd.sh

The same directory also contains setup.systemd.sh. When executed, it copies scripts to /usr/local/bin and configures systemd to run the script enable-brightness.sh on boot.

./setup.openrc.sh

The same directory also contains setup.openrc.sh. When executed, it copies scripts to /usr/local/bin and configures OpenRC to run the script enable-brightness.sh on boot using the local service.

To build your own patched tree use the patch.sh scripts located in the scripts folder. The script accepts two arguments which correspond to the git branch and tag of the kernel tree to build the patch against. Example:

./patch.sh 4.3 4.3.4

This script clones the two trees, diffs the necessary files and create a patch. It then applies this generated patch and the other included patches to the original tree. This process results in a patched tree located in build/linux-patched.

If you're reading this either the sound.sh script failed or better you want to understand what it does :)

The first thing to do is to copy over the firmwares from the firmware directory to wherever your distribution installs firmwares (usually /lib/firmware or /usr/lib/firmware).

Next it's a good idea to make sure that the internal card driver always uses slot 0 in Alsa so that any PulseAudio configuration done later can reliably address the card. This is done by adding a .conf file in /etc/modprobe.d containing the following line:

options snd slots=snd_soc_sst_bdw_rt5677_mach,snd-hda-intel

At that point you may want to reboot. Once rebooted check the output of aplay -l, you should see something like:

**** List of PLAYBACK Hardware Devices ****
card 0: bdwrt5677 [bdw-rt5677], device 0: System Playback (*) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

If that's not what you are getting then check for errors in dmesg.

Once the driver loads correctly enable the "HiFi" verb with ALSAUCM. Make sure alsaucm is installed. It's usually part of the "alsa-utils" package. Assuming alsaucm is present, run the following:

$ cd scripts/setup
$ ALSA_CONFIG_UCM=ucm/ alsaucm -c bdw-rt5677 set _verb HiFi

Next the microphone driver must be loaded statically by PulseAudio, add the lines:

load-module module-alsa-source device=hw:0,1
load-module module-alsa-source device=hw:0,2

to /etc/pulse/default.pa before the line

load-module module-udev-detect

Restart PulseAudio with:

$ pulseaudio -k && pulseaudio -D

If PulseAudio fails to restart running it in the foreground may produce helpful output:

$ pulseaudio

Assuming PulseAudio restarted successfully the last thing to do is to restore the alsa state:

$ cd scripts/setup
$ sudo alsactl restore --file alsa/asound.state

Some users have also reported needing to configure PulseAudio to load the output driver statically, this can be done by adding the following line in /etc/pulse/default.pa:

load-module module-alsa-sink device=hw:0,0

This repo exists so that we can all benefit from each other's work. Thomas Sowell's linux-samus repo was both an inspiration and help in building it. The hope is that others (you) will also feel inspired and contribute back. PRs are encouraged!