When setting up Arch Linux (or any Linux distro. for that matter) I find that the screen is very dark so much so that I cannot even set up the system with out an external monitor. The following fix may be able to clear up Intel i915 related brightness issues on other machines but I have only tested it with my Gateway NV78.
Go ahead and set up Arch with the help of an external monitor and when you get it pretty well set up create this file:
setpci -s 00:02.0 F4.B=40
Now make the new script executable by running this command:
sudo chmod +x /usr/local/bin/brightnessfix
You should at this point be able to type
sudo brightnessfix into your terminal and have your brightness restored. To make it run on start up create this systemd service:
Description = "Fix for screen brightness issue"
Activate it by typing this command:
sudo systemctl enable brightnessfix.service
Now we should be at the point were the screen lights up after the computer boots. We are not done yet, edit your kernel line to add the following two options:
quiet acpi_osi=Linux acpi_backlight=vendor
This is what mine looked like before and after the change:
GRUB_CMDLINE_LINUX_DEFAULT = "quiet"
GRUB_CMDLINE_LINUX_DEFAULT = "quiet acpi_osi=Linux acpi_backlight=vendor"
Now we are going to push the change to our active grub config with this command:
sudo grub-mkconfig -o /boot/grub/grub.cfg
Okay, I think we are done. Now you should be able to use the brightness keys even if the computer’s backlight is completly off! Also it should come out of sleep or when you open the lid from it being closed with the correct brightness.
Wait! My system doesn’t use systemd. How can I apply a comparable start up script to turn on my backlight?
Instead of creating a “brightnessfix” file in your path just put
setpci -s 00:02.0 F4.B=40 into your /etc/rc.local file and it will run after system boot. Don’t forget to add the extra options to grub and you should be good to go.