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How to Fix Brightness Keys Not Working in Ubuntu

Linux distributions like Ubuntu have always faced the problem of compatibility with different devices. Although lately most of these problems have been fixed in newer releases, they still exist in older versions for particular type of devices.

One such problem which is widely faced by many Ubuntu users is that of non working “Brightness Control” keys on the keyboard.

To fix brightness keys in Ubuntu, follow the instructions below:

Open /etc/default/grub in either vim or any editor of your choice.

sudo vim /etc/default/grub

The variable GRUB_CMDLINE_LINUX_DEFAULT is the one we have to modify. Change it the following:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor acpi_osi=linux"

Save the file. If you used vim, press Escape to go to the vim command mode, then type :wq to save the file and exit vim.

ACPI is a power interface management standard which is implemented in operating system kernels. By default Linux kernel uses an inbuilt driver for keyboard keys, which is often non compatible with some keyboards.

Hence, we specify the option acpi_backlight=vendor which tells the kernel to take precedence of vendor driver over kernel driver. The option acpi_osi=linux tells the kernel to enable inbuilt ACPI workarounds for Linux drivers; which can be the case if the device driver has issues for Linux architecture.

Finally, run update-grub for the change to take place.

sudo update-grub

After this, the brightness keys should start working.

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