Gnome-shell cannot adjust screen brightness on dell laptop with intel graphics

On my dell laptop (XPS 13 developer) running Fedora 21 I am in a situation similar to this, or this. I can give some more details tough.

Under directory /sys/class/backlight I have:

dell_backlight/brightness
intel_backlight/brightness

Where the first is brought-in, I guess, by dell_laptop module, while the second comes from i915. Trying to adjust screen brightness works with intel_backlight only (by echoing values), while trying to fiddle with other makes no change, with no errors.

The problem is that gnome3 menu settings, and the hotkeys, both try to work around dell_backlight (the hotkeys management should be in dell_wmi module).

Is there a way to make GNOME use the other, by some setting in gconf maybe? Or just to rewire the hotkeys and the slider to some script?

Edit:

My laptop has a:

Intel Corporation Haswell-ULT Integrated Graphics (rev 09) (prog-if 00 [VGA controller])
Subsystem: Dell Device 060a
[...] 
Kernel driver in use: i915

This works (with gnome running or not):

echo 250 > /sys/class/backlight/intel_backlight/brightness

This does not:

echo 250 > /sys/class/backlight/dell_backlight/brightness

I know that gnome-shell is trying to adjust dell_backlight and not intel_backlight, because using the brightness slider in the tray menu, I can read value changes in dell_backlight.

Asked By: guido

||

You could probably just shortcut:

xbacklight -dec 10 & xbacklight -inc 10 to whatever keys you want. I do this in Fluxbox like so:

echo "232 :Exec xbacklight -dec 10" >> ~/.fluxbox/keys
echo "233 :Exec xbacklight -inc 10" >> ~/.fluxbox/keys
Answered By: ryanpcmcquen

I would remove dell_backlight/brightness

I would then add:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=intel"

To your grub file then:

update-grub
Answered By: Michael Prokopec

I ran into this problem with an older Intel-based Dell laptop. The accepted answer here (adding "acpi_backlight=intel" into the GRUB config) did not work for me. What finally did work was a different GRUB setting.

Open /etc/default/grub for editing.

Find the line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and add pcie_aspm=force acpi_backlight=native to it so that the whole thing looks liek

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=native"

Then run sudo update-grub and reboot.

Answered By: Pockets
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