added backlight info

content/posts/Lenovo-slim.md

@@ -3,6 +3,7 @@ date = '2025-12-19T22:51:02-07:00'
 draft = false
 title = 'Lenovo Slim'
 tags = ['install', 'guide']
+lastmod = '2025-12-19'
 +++
 
 ## Getting rid of Windows
@@ -138,6 +139,7 @@ Upon rebooting we're going to finish setting up the system, see here for more re
 - [Install our user environment](#install-user-environment)
 - [Setup window manager](#setup-window-manager)
 - [Setup fido2 login](#fido2-login)
+- [Brightness control](#brighness-control)
 
 ## Add a user
 
@@ -250,6 +252,18 @@ If that worked we can setup login. Make sure you have a working password for roo
     auth    sufficient  pam_u2f.so cue origin=pam://hostname appid=pam://hostname
 
 
+### Brightness control
+
+The brightness buttons do not work out of the box, fortunately there's a utility to help: [brightnessctl](https://github.com/Hummer12007/brightnessctl). In our dotfiles there's a new utility called monbright that similar to our volumeset, sets the bightness of the monitor. We connect it to the buttons in the configuration for swaywm. Getting it to work required adding my user to the video group
+
+    sudo gpasswd -a *user* video
+
+Then add a udev rule to change the group on the interface to video so members of the video group can change the setting, see [Backlight](https://wiki.archlinux.org/title/Backlight)
+
+    /etc/udev/rules.d/backight.rules
+    --------------------------
+    ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video $sys$devpath/brightness", RUN+="/bin/chmod g+w $sys$devpath/brightness"
+
 ### Conclusion
 
 Everything on this laptop seems to work great out of the box so far. The only thing that is bugging me is the WIFI. It seems to start slow and ramp up, not sure if it's the arch mirrors right now with the ongoing DDOS issues or if it's something in the wifi driver.