Solve back-light (brightness) problem in Ubuntu/Kubuntu

With Kubuntu 18.0.4 as my current working OS for my day to day home use, I am recursively facing a disabling back-light/brightness problem. In general, every time my Ubuntu updates with the latest packages, and grub is modified; My screen goes dim and keys to change the brightness doesn’t work. So, in this edition of my technology notebook, I am writing the possible solution that works for me. For reference, I am using Panasonic CF-SX2, with Intel CPU and no GPU(s).

Note that, this particular solution might not be general enough to accommodate diversely available systems. However, if you are working with Ubuntu/Kubuntu/Lubuntu system with base version ubuntu 18.0.4, there is a high possibility that it might work.

So first we need to change the grub file at /etc/default/grub

The file would look something like the one given below;

On the highlighted line change the code as below and save the file.

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=video"

After making change on the grub file, we will need to create a new configuration file as

/usr/share/X11/xorg.conf.d/80-backlight.conf

In this new configuration file we will need to add the following options and save it

Section "Device"
    Identifier  "Intel Graphics"
    Driver      "intel"
    Option      "AccelMethod"     "sna"
    Option      "Backlight"       "acpi_video0"
    BusID       "PCI:0:2:0"
EndSection

Once every thing is done, update grub with sudo update-grub, and reboot the system to implement the changes.