Hi, folks
I'm having a problem trying to change screen brightness with laptop function keys. The response time is really slow and stuttery.
If I set a keyboard shortcut to the action it works flawlessly, as you can see in the short video bellow. In the video, for some reason, when I lowered the volume with Fn key it went fast, although not as fast as alt. shortcut, but it's not the usual behaviour.

https://drive.google.com/file/d/1BSzsz9Ss6Of2Me0CtYIq-PEDGNh5luE9/view

I've been looking for a solution for a few hours already, with no avail.
Can someone tell me what could be happening?

Hi!

You could check the keys using `evtest` as root and selecting your keyboard input device. Depending on the implementation you won't see key presses using the provided keys. That means they are handled internally without the knowledge of the operating system. In Plasma you get OSD-messages for those changes as it is watching the backlight for file changes. If this is the case the only thing that could help is a firmware update (uefi update). Check the vendors support pages.

If you get key press events like XF86BrightnessAdjust or XF86MonBrightnessUp we can investigate. As a simple test you can check setting the brightness manually (again with root permission, so be careful for typos).
In /sys/class/backlight there should be a subfolder like intel_backlight which contains the file brightness and max_brightness. Simply echo a value to the brightness file that is above 0 and below max_brightness, e.g. `echo 200 > /sys/class/backlight/intel_backlight/brightness` (with sudo echo won't work, use `tee` instead).
In parallel you could check `libinput debug-events` while pressing those keys.