If you have installed and running Ubuntu 12.04 on Hewlett Packard (HP) manufactured laptop like pavilion models, you may be facing this issue.
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Issue : Whenever you start your laptop and before landing in the Login screen, the display brightness may go Zero (i.e you will be seeing a blank screen).
Brightness can be set back by pressing the dedicated brightness function keys to increase and decrease them. But here is the permanent fix for it.
Step 1: Open Terminal and navigate to the default folder in the etc folder like below
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cd /etc/default
Step 2: You have to open the Grub file present in that directory to edit it using any of your favorite text editor and here we use Gedit, do like below
sudo gedit grub
Provide your password to open the file.
Step 3: Now you would have opened the grub file and find the line which says GRUB_CMDLINE_LINUX=” “
Add the below line in-between those quotes, save the file and close the editor
acpi_osi=Linux acpi_backlight=vendor
The file should appear like this after editing.
Step 4: Time to update your changes that you made to the grub file. In the terminal type the below command
sudo update-grub
Provide your password to update the grub.
Step 5: Restart your system to check, if the changes work. If you encounter any problem, comment here we would help you resolving it.
Thank you.
