screen brightness change doesn't work with tested NVidia drivers

[autumna]

16.04 (live CD, with persistence) also 14.04 full install as well

1) Switch drivers from nouveau to Nvidia
2) restart the computer
3) the brightness controls doesn't work.

Current workaround:
using xbacklight and creating custom toolbar buttons and mapping shortcuts manually.

[Kaj Ailomaa (zequence)]

Pretty sure the backlight setting is not done through graphic drivers, but I could be wrong.

Did you test screen brightness with nouveau drivers?

[autumna (autumna)]

it was working with nouveau, because it is one of the first things I tested. I switched drivers and it wasn't working anymore.

and apparently this has happened before too with XFCE https://bugs.launchpad.net/ubuntu/+source/xbacklight/+bug/1511127

I am actually not sure if it is nvidia driver itself, or the driver switching messing up xorg.conf or something else. My ISO usb is currently is no longer booting at the moment but I will retest the whole thing again once I fix that.

[autumna (autumna)]

ok. again with 16.04 liveusb with persistence.
1) with nouveau drivers (default, fresh install): brightness control works
2) switch to nvidia (proprietary, tested)
3) brightness control still works
4) reboot
5) brightness control doesn't work.
6) change back to nouveau
7) brightness control doesn't work
8) reboot
9) brightness control works

also random artifact: the spinning wheel login screen animation doesn't show after step 4 reboot (instead a much older login screen is showed), but it is back after the step 8 reboot, not sure if it is related or not.

[Kaj Ailomaa (zequence)]

Thanks for doing more testing. Since this bug appears to involve the nvidia package, I changed the "affects" to the source package for nvidia-current.