This is similar to these two questions, but the solutions posted in each do not help me:
- xbacklight - No outputs have backlight property
- xbacklight: No outputs have backlight property - No /sys/class/backlight folder
I just got a Dell XPS 9380.
I'm using Ubuntu 18.04 with the i3 window manager, and I'm trying to get nice hotkeys set up to change the backlight brightness, among other things.
I want to use xbacklight to alter the brightness. But it tells me "No outputs have backlight property", and indeed if I run
xrandr --verbose I don't see backlight properties anywhere.
I can set the brightness by putting numbers in
/sys/class/backlight/intel_backlight/brightness, so I don't think I need to mess with any kernel options.
Now, the other questions' solutions, and the section about xbacklight on the Arch wiki say to add a Device section to the
xorg.conf file, to set the
Backlight option to
All of the examples have
Driver set to
intel. When I do that and restart X, everything slows to a crawl, but I can use xbacklight successfully, and I see a backlight section in
xrandr --verbose. But the CPU is pinned -- I think it's not really using the intel driver but rather a framebuffer. I don't know how to be sure. Here's an example configuration, which I put in
Section "Device" Identifier "Card0" Driver "intel" Option "Backlight" "intel_backlight" EndSection
If I instead set
i915, everything is fast again, but xbacklight now gives the error again.
From searching the web I haven't been able to get a handle on what the difference is between
i915. I get the impression
i915 is the Intel driver, but then I'm not sure why all the examples set
Driver "intel". If they're different and I should be using
intel, maybe I don't have that one installed? I tried installing the
xserver-xorg-video-intel package, which required me to remove a bunch of other packages including
xserver-xorg-video-intel-hwe-18.04 (these two both claim to be drivers for Intel i9xx), then setting
Driver "intel", but this resulted in a black screen I couldn't get out of (even with control-alt-F combos) and I had to reboot.
Any help would be appreciated.