After long inquiry into Linux compatibility I have bought a Dell Latitude E7450 and installed OpenSuse 13.2 that supported all hardware out of the box - including the touchscreen. I changed to tumbleweed in order to update some software and everything went fine for quite a time with different kernels. I am now using 3.19.x-y-desktop kernels, still having a 3.16.2-x-desktop at disposal. All of a sudden, must have happened after a system update, the function keys for brightness stopped working and a setting of the brightness by the gnome controls as well. I tried with xbacklight -set 0 (50 or 100) but no change neither. The brightness seems to be unchangable and seems to be set to a high level by default thereby draining on the battery life which is much worse than advertised anyway.
I tried all of the kernels at hand with no difference in success. I never updated the BIOS of the machine, btw. The graphic seems to be by intel, in the yast2-hardware information I can only see a hint at it in the section Display (Intel VGA compatible controller).
Is there a way to get brightness working again or to revert to 13.2 stable after many updates and additional software installations being made?
Thanks in advance for contributions.