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 intel_backlight
.
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 /usr/share/X11/xorg.conf.d/20-video.conf
:
Section "Device"
Identifier "Card0"
Driver "intel"
Option "Backlight" "intel_backlight"
EndSection
If I instead set Driver
to 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 intel
and 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.