Ubuntu: Brightness keys do not work: gmux_backlight and nv_backlight



Question:

I installed Xubuntu 16.04 on my MacBook Pro 6,2 (mid 2010 model, so it's old!). I cannot get the brightness keys to work.

After searching for help, I knew to look in /sys/class/backlight. In it, I found two directories gmux_backlight and nv_backlight.

Here's what I discovered:

  1. The brightness keys on my keyboard would change the brightness values in nv_backlight. However, these had no effect on the actual screen brightness.
  2. If I manually edit the brightness values in gmux_backlight, then the screen brightness would adjust accordingly.

So this seems to suggest that I need to get the brightness keys to modify the values in gmux instead of nv. How should I do this?

(Also, many places suggested installing the Nvidia drivers. However, when I tried that (installing version 340.96) and restarted, I would boot to a blank screen. I had to re-install Xubuntu.)


Solution:1

A workaround could be to create such a key-binding that will edit gmux_backlight/brightness if you're stroke your keys for brightness. Unfortunately I have no Xubuntu running, so I'm not sure if you can configure this via Settings-Manager xfce4-settings-editor or you have to use xbindkeys essentially you could execute a shell script. For example the shell script which reads the current brightness-value and reduce it would look like:

backlight=`cat /sys/class/backlight/gmux_backlight/brightness`;  if [ $backlight -gt 1 ]; then         backlight=$((backlight - 1));         echo $backlight > /sys/class/backlight/gmux_backlight/brightness;  fi  


Solution:2

If using refind activate the spoof_os_x_version setting. You can also use this tool https://github.com/0xbb/apple_set_os.efi. I went with the second option, because this was not messing my Windows boot as the first one did.

This fool your computer by forcing to initialize like if it was booting os x... there are special efi vars for this. Apparently that Apple don't want you to use the dual gpu so easily on other OS.


Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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