Dimming Screen Backlight Below System Defaults

Hello everybody,

I recently bought a Dell Inspiron i3459 i561T BUs laptop on the Internet. It came with Ubuntu 14.04 preinstalled. As soon as I got it, I upgraded it to Ubuntu MATE 16.04.1. It generally works fine. The problem is that the screen is too shiny, and even when I set the MATE desktop brightness applet to 1% it’s still too bright. In 14.04 I used to activate the Brightness Controller when I needed it, but it doesn’t work on 16.04. I found a workaround on my older laptop when 16.04 came out, and it was to run, for example

xrandr --output LVDS1 --brightness .5

In this new computer, it should be

xrandr --output eDP1 --brightness .5

However, that command doesn’t work at all. I tried xgamma, xbacklight, f.lux, Iris… and nothing worked. The only thing I can get the laptop to do with any of those commands and apps is to set it at 1%, but not below that. I looked for some updated information about this issue and some people suggest you change some kernel options and system files or redirect to some Arch info. I’m afraid I’ll end up breaking something on the system.

Any thoughts or ideas on this issue? Should I go back to 14.04? I really love Ubuntu MATE 16.04 as it is.

Thanks for your help.

It seems to be a kernel-related problem. I chose the advanced options in the grub menu and ran the 4.4.0-31 kernel (the one that was on the image I used when I installed 16.04 on this Dell laptop). The xrandr --output eDP1 --brightness .5 command worked just fine. What might be the problem with the newer kernel then? Is there a workaround so that I can use the latest stable kernel?

The issue completely disappeared with the 4.4.0-36 kernel upgrade.