*UPDATE* March 10th, 2019
I have to update my post because the previous fix does not work anymore with recent versions of debian + GNOME 3, on the same laptop as before (sandybridge core i3).
Now, you have to follow this suggestion given by people all around the world: edit the /etc/default/grub file in super user mode and insert
acpi_backlight=none to the
GRUB_CMDLINE_LINUX_DEFAULT variable. For example, here is what I have:
After editing this file, run
sudo update-grub and reboot. Backlight keys should work now.
You can get rid of the 20-intel.conf file if you have used it.
Time spent to get the info: one day. Length of the fix: a few lines. Haha, this is so ridiculous it makes me smile a little.
Okay, so you are:
- on fresh Debian Jessie (GNOME 3),
- on a laptop,
- with an integrated graphics unit,
- and it is an Intel CPU. In my case, I have a Core i3 Sandy Bridge CPU with HD Graphics 3000.
The backlight function keys:
- are working so you have an on-screen display feedback,
- are not changing the effective brightness of your screen,
- are changing the values of this file:
/sys/class/backlight/acpi_video0/brightness(close and reopen in gedit to see the value changing or check by command line).
You have this folder:
Yay! You may have a solution!
- Create a file:
1sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
- Add this in the file:
123456Section "Device"Identifier "card0"Driver "intel"Option "Backlight" "intel_backlight"BusID "PCI:0:2:0"EndSection
- Save file.
- Close gedit.
- Restart the computer.
- It should work now!
If this fix does not work on your laptop, I am sorry to hear that but I cannot help you further. Don’t ask the noob. I have just followed guidance on linux threads such as here: link to Ubuntu’s launchpad website. Good luck!