Fixing low brightness in GNU linux mint

First attempts to fixing
The fix (wip, hopefully coming)
Useful/additional information

This is a common problem in recent distributives of linux, according to my searches online.

After a fresh installation of Mint (xfce version, a very pleasant lightweight operating system) on [yet another] my laptop, I noticed that the brightness of the monitor was low.

Sometimes the system did respond to pressing brightness buttons on the keyboard (Fn+Brightness Up/Down), but the response was weird and chaotic.

The brightness could go from very low to (probably) maximum brightness in 1 key press. Or most often it just showed brightness control bar changes – but didn’t effect brightness.

First attempts to fixing
* I tried updating the system by installing all new offered updates
* I checked whether there would be some new driver offered through the driver manager. No new drivers were found there
* Power management also checked, all setting were set for 100% brightness – still the monitor was rather dim.

* Easy attempt:
I had a good and simple idea: searching information by mentioning the actual video card of my laptop, Mobility Radeon HD 3200:

First search result is exactly what I was looking for:
ATI Mobility Radeon HD 3200 Proprietary Driver … – Linux Mint

After the appropriate driver for linux (a proprietary driver, unfortunately) was downloaded, gdebi package manager opened up and continued installation (NB*: I got a warning, that installing the newest driver might lead to unstable operation – but I thought I had nothing to loose as machine was not functioning properly anyway =). A reboot… and crippled monitor resolution as a result of [too] new video driver! The warning was relevant (and you should never use new [== unstable] video drivers for linux, probably).

To remove ATI Radeon drivers, which proved to be not very functional for this machine, I used the following cli command:
~ $sudo apt-get purge fglrx*
After a reboot, the resolution and proportions of the monitor came back to normal. Actual brightness control still didn’t respond to Fn+Brightness keys…

The fix
Finally, I found the solution, it came from the Linux Mint forum:

I had to edit grub file (in my case, by modifying one line to: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"), and then save the file and update grub:
sudo update-grub

The brightness control is now functioning.


Useful/additional information

# Additional cli command:
~ $ ls /sys/class/backlight/
This is what i got:


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