Screen brightness

If you've had Debian on a few boxes you've bound to come cross one with the brightness keys not functioning.

Here are some methods I found to get them working - though the Arch wiki page is much more informative.

1. GRUB

sudo nano /etc/default/grub

Change this line
GRUB_CMLINE_LINUX_DEFAULT="quiet splash"

to
GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_backlight=vendor"  

then run
sudo update-grub  

But you may need to specify to the Xorg what device driver to load, e.g Intel.

Create or edit xorg.conf:
sudo nano /etc/X11/xorg.conf  

add the lines for your devise, e.g. for Intel:
Section "Device" Identifier "Device0" Driver "intel" Option "RegistryDwords" "EnableBrightnessControl=1" EndSection  

2. xrandr

xrandr --output LVDS-1 --brightness 0.8

but I found this fades the screen colours

3. xbacklight

install xbacklight and run
sudo xbacklight -10  

get error: No outputs have backlight property

4. setpci

e.g.

sudo setpci -s 00:02.0 F4.B=[value 1-ff]


We can use scripts to bind setpci commands to keys (and here using openbox keybinds)...

• make two scripts, named br-up and br-dn

content for br-up:
#!/bin/bash # these are the possible values: # 42 56 70 92 AF CC E5 FF # 30 40 50 60 70 80 90 100 % Current=`sudo setpci -s 00:02.0 F4.B` case $Current in 10) sudo setpci -s 00:02.0 F4.B=20 ;; 20) sudo setpci -s 00:02.0 F4.B=30 ;; 30) sudo setpci -s 00:02.0 F4.B=42 ;; 42) sudo setpci -s 00:02.0 F4.B=56 ;; 56) sudo setpci -s 00:02.0 F4.B=70 ;; 70) sudo setpci -s 00:02.0 F4.B=92 ;; 92) sudo setpci -s 00:02.0 F4.B=af ;; af) sudo setpci -s 00:02.0 F4.B=cc ;; cc) sudo setpci -s 00:02.0 F4.B=e5 ;; e5) sudo setpci -s 00:02.0 F4.B=ff ;; esac  

content for br-dn:
#!/bin/bash # these are the possible values: # 42 56 70 92 AF CC E5 FF # 30 40 50 60 70 80 90 100 % Current=`sudo setpci -s 00:02.0 F4.B` case $Current in ff) sudo setpci -s 00:02.0 F4.B=e5 ;; e5) sudo setpci -s 00:02.0 F4.B=cc ;; cc) sudo setpci -s 00:02.0 F4.B=af ;; af) sudo setpci -s 00:02.0 F4.B=92 ;; 92) sudo setpci -s 00:02.0 F4.B=70 ;; 70) sudo setpci -s 00:02.0 F4.B=56 ;; 56) sudo setpci -s 00:02.0 F4.B=42 ;; 42) sudo setpci -s 00:02.0 F4.B=30 ;; 30) sudo setpci -s 00:02.0 F4.B=20 ;; 20) sudo setpci -s 00:02.0 F4.B=10 ;; esac  


• put in your scripts dir and make executable with chmod +x or thunar right-click custom action
• next, edit your sudoers file so as to not need to enter sudo password for setpci (otherwise there will be no effect pressing the brightness keys)
sudo nano /etc/sudoers  


• add the line
ALL ALL=(ALL) NOPASSWD: setpci  


• map keys to the scripts - with Openbox this is done in the file lxde-rc.xml or rc.xml in ~/.config/openbox/
e.g.

<keybind key="W-Up"> <action name="Execute"> <execute>~/scripts/br-up</execute> </action> </keybind> <keybind key="W-Down"> <action name="Execute"> <execute>~/scripts/br-dn</execute> </action> </keybind>  


• then set the new keybindings with: openbox --reconfigure
• set the brightness level at start-up with a line in your autostart file...

   for LXDE: @sudo setpci -s 00:02.0 F4.B=CC in ~/.config/lxsession/LXDE/autostart

   for Openbox: sudo setpci -s 00:02.0 F4.B=CC in ~/.config/openbox/autostart


• or, make .desktop files in ~/.local/share/applications with the same script commands, name them, set icons and add them to a panel as launchers

another way....setpci-making-a-script-to-manually-change-brightness