From eb385fad1e6dcbe4289ff88b0095ac0791931677 Mon Sep 17 00:00:00 2001
From: Daniel Ebbert <daniel@ebbert.nrw>
Date: Wed, 18 Aug 2021 11:58:49 +0200
Subject: [PATCH] lenovo/thinkpad/e495: use native acpi backlight

---
 lenovo/thinkpad/e495/default.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lenovo/thinkpad/e495/default.nix b/lenovo/thinkpad/e495/default.nix
index 51ddb5c..60f8efb 100644
--- a/lenovo/thinkpad/e495/default.nix
+++ b/lenovo/thinkpad/e495/default.nix
@@ -8,4 +8,10 @@
 
   # see https://github.com/NixOS/nixpkgs/issues/69289
   boot.kernelPackages = lib.mkIf (lib.versionOlder pkgs.linux.version "5.2") pkgs.linuxPackages_latest;
+
+  boot.kernelParams = [
+    # Force use of the thinkpad_acpi driver for backlight control.
+    # This allows the backlight save/load systemd service to work.
+    "acpi_backlight=native"
+  ];
 }