The keys fn+F5 and fn+F6 do not change the brightness on my Asus Zenbook UX305.
I can change the brightness from the command line with this command:

xrandr --output eDP1 --brightness 0.5

This example reduces the brightness to 50% of the rather bright default on the UX305.

But how can I use the default keys (see above) to change the brightness?

Warning: Do not use a brightness value greater than 1.0. Damage to your screen or eyes may result.

Hardware: Asus Zenbook UX305, UX303UA, ...
Ubuntu: 14.04, 16.04

Related: How to Enable Brightness Buttons in 16.04 of Zenbook?


2 Answers 2


I am having the same problem with the newer UX305CA. Apparently it is really common since the hardware is not recognized, so I just assigned a new shortcut. Following this answer:

sudo apt-get install xbacklight

Then assign new shortcut:

  • Settings > Keyboard > Shortcuts > Custom Shortcuts > +

Add those two:

  • Brightness up: xbacklight -inc 10
  • Brightness down: xbacklight -dec 10

Then click on each of the Disabled and select the new shortcut. In my case I used Alt+F5 and Alt+F6 (since I use Ctrl+F5 for web dev).

If you want, you can also mess with the boot options to fix it:


I have the same problem. there is a workaround although.

add "acpi_osi=" at the and of the kernel boot parameters.

to permanently do this edit /etc/default/grub as root and add "acpi_osi=" at the end of GRUB_CMDLINE_LINUX_DEFAULT then run "update-grub" as root

after that brightness and all other hotkeys work but the ambient light sensor is no longer detected. But this is not a big problem since there is no standard ambient light regulation of screen brightness anyway

  • Zen UX305UA / 16.04 LTS: xbacklight works, but brightness keys(FN + F5/F6) are not recognized. acpi_osi detects keys correctly, but has no effect (brightness doesn't change at all, neither through hotkeys, brightness app nor xbacklight)
    – Jan Groth
    May 17, 2016 at 10:57
  • Have you tried to use the modesetting package? Please, see askubuntu.com/q/816264/25388 Aug 27, 2016 at 21:36

If you are interested by auto brightness for this notebook (through ALS sensor) it can help to you: https://github.com/Perlover/Asus-Zenbook-Ambient-Light-Sensor-Controller/tree/asus-ux305 It works at my Asus UX305 ;-) But you need to blacklist acpi_als module before

  • Is there anything related in apt-get? It would be great to understand this part also better. Aug 27, 2016 at 21:37

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