Erratic brightness control on Thinkpad X200T

Support & Help Requests Hardware
#1

Hello!
I’m fairly new to MATE but not ubuntu in general

I’ve just installed Ubuntu MATE 16.04.3 on my old Thinkpad X200 tablet. Everything’s been working great except for an issue with screen brightness. I should clarify that it only seems to affect the keyboard brightness control, and if I use the slider either with the panel plugin or the power manager it works fine.

When using the keyboard controls, changing the brightness works but when I bring it lower (maybe sub 30%?) the screen starts flickering on and off when changed. The popup GUI also doesn’t display the current brightness properly, and the value it shows seems increase and decrease exponentially.

I’ve also ran Fedora MATE and Solus MATE live systems before and this same issue occured.

#2

Here is a short video demonstrating what’s going on.

#3

I’ve found a similar problem on github. Sounds like it’s about the BIOS and power manager interacting. I’m not sure what to do from here on, this is way above my league.