appsforartists/Linux for the Lenovo Legion Go.md

## Linux for the Lenovo Legion Go.md

      
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              Linux for the Lenovo Legion Go.md
            
          
    I've been experimenting with running Linux (specifically NixOS) on the Legion Go.  I intend to publish my configuration when it's in a good spot, but also thought it would be handy to have a shared space to document what we all learn in the mean time.
I'm admittedly new to both Linux and Nix, and appreciate any advice others can share too.
What's working


Touchscreen
Basic gamepad when both controllers are attached/detached
Rumble
Legion L+X to change perf modes
Sound + volume control
Power button (when not in Steam - I probably need to tweak my Jovian packages)
Trackpad
FPS mode (using the right controller as a mouse)
WiFi
USB keyboard
Bluetooth

What's not yet working


Rear paddles
Legion L/R buttons
Most buttons when only one controller is attached
Changing the display brightness (this seems to be a Steam gamescope problem - sudo xbacklight works)
The battery indicator
I tried running American McGee's Alice and the Go would abruptly turn off sometimes.  I'm not sure if it's a heat management problem or a general stability problem.  (I've been so busy trying to get this to work that I haven't had time to play much on it.  I did finish Desk Job with no issues.)

What doesn't work


Booting from the SD card slot (doesn't appear in the boot menu)
Booting from a DVD (Apple SuperDrive over USB)

Setup

I shrunk the Windows partition to 200G, made a FAT32 boot partition, and formatted the rest as btrfs.  home, swap, and nix are subvolumes in btrfs.
NixOS ships with an old kernel.  The screen will flicker (unless it's being touched, or the CPU is under load) until you upgrade to the latest kernel.
The kernel needs a couple patches to fix the display orientation and enable the gamepad.  I've submitted both for inclusion in the future kernel, but in the mean time, include this section in your configuration.nix to get the basics working:
  boot = lib.mkMerge [
    {
      initrd.kernelModules = ["amdgpu"];
      loader = {
        systemd-boot.enable = true;
        efi.canTouchEfiVariables = true;
      };
    }

    (lib.mkIf (lib.versionOlder pkgs.linux.version "6.8") {
      kernelPackages = lib.mkDefault pkgs.linuxPackages_latest;
      kernelPatches = [
        rec {
          name = "legion-go-display-quirk";
          patch = pkgs.fetchpatch {
            name = name + ".patch";
            url = "https://github.com/appsforartists/linux/compare/master...legion-go-display-quirk.patch";
            sha256 = "sha256-BfqrFUQutcTMlzQdsKvOLhRUIo+63S1imWab4QjBO6c=";
          };
        }
        rec {
          name = "legion-go-controllers";
          patch = pkgs.fetchpatch {
            name = name + ".patch";
            url = "https://github.com/appsforartists/linux/compare/master...legion-go-controllers.patch";
            sha256 = "sha256-2OX8hlsjbqANV1cwZjT4+e5pvLGSNQ/Eh92HK9yT6z4=";
          };
        }
      ];
    })
  ];
I'm using Jovian to run the SteamOS UI (gamescope) on my Go.  Using Settings > Controller > Test Device Inputs > Setup Device Inputs, I was able to map the buttons under the D-pad (with the hamburger and change window icons) to menu and capture.  This is both what they should have been mapped to originally, and enables gamescope to be usable (since it expects you have a menu button).
Things that need investigation/assistance

Better hardware support

I'm only a couple evenings into this project. I'm happy to have the basics working, but there's still plenty I haven't sorted out yet.
I know there are RyzenAdj and LenovoLegionLinux packages that are probably useful.  I did try to use the latter by adding this to the above boot attribute set:
extraModulePackages = [config.boot.kernelPackages.lenovo-legion-module];
That put legion_cli on my command line, but it wasn't finding hwmon.  I haven't yet investigated further, but I have shared the logs for onboarding a new device in that repo.
Gamepad paddles, Legion buttons, mapping

Since this was originally designed to be a Windows device, it appears the gamepads use the Xbox 360 controller API.  That's supported in the Linux kernel by xpad.
I tried the simplest things (passing MAP_PADDLES into the config, or using the Xbox One controller API), but neither made the extra buttons functional.  I also did some stabbing-in-the-dark with libinput and jstest, but couldn't find the events being sent by those buttons.
I suspect if we could log the data value being passed to xpad_process_packet, we could figure out the indicies for each of the missing buttons and wire up the mapping.
I'm new to Linux and not a C programmer, so I suspect others may have an easier time with this piece of the puzzle than I have so far.
Thanks

Massive thanks to @samueldr and @JovianExperiments for their help in this process so far.  I wouldn't have ever been a kernel patcher without their encouragement and guidance.
Let's collaborate

If you've tried running Linux on your Legion Go, please share what you've learned (what worked, what didn't, and how you set it up) in the comments below.  Let's get this thing working!