I installed Ubuntu 20.04.1 LTS on my MacBook Pro 15" Mid 2014. As many others, I can not get the brightness adjustment to work. Whenever I press the corresponding keys
F2 the brightness adjustment does pop up and reacts, but the actual brightness of the screen always stays on max (I presume, something very bright) and does not change.
It is a fresh install and it does have a NVIDIA GeForce 750M Mac Edition.
Not working Solutions
So far I have tried manually adjusting the brightness via
echo 4 | sudo tee /sys/class/backlight/acpi_video0/brightness
which did not work.
I have also tried adding
setpci -v -H1 -s 00:01.00 BRIDGE_CONTROL=0
Lastly I tried adding
Section "Device" Identifier "Device0" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce 750M Mac Edition" Option "RegistryDwords" "EnableBrightnessControl=1" EndSection
/usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf as was suggested in this question.
None of those solutions have worked for me, but I also haven't find any working solutions for my particular GPU or an Ubuntu Version above 20.
I am quite new to Linux in general and also this forum. Therefore I apologize in advance should there be some easy fix or whether I have overlooked one of many questions with the correct solution.