[SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

Markus00000 · 2013-04-17 08:52:28

For a long time it hasn't been working to adjust the display brightness with the Fn key on my Dell Latitude E6530 with Intel HD graphics on xmonad on Arch. It did work before.

It is still working on Ubuntu, openSUSE and Windows without any configuration.

Other Fn functions like changing the backlight brightness of the keyboard still work.

I can still change the display brightness with:

echo 1234 > /sys/class/backlight/intel_backlight/brightness

or via xbacklight. The value in /sys/class/backlight/intel_backlight/brightness doesn't change when using the Fn key.

Due to my system settings, the display blanks after several minutes to save power. When it's awakened afterwards, the brightness will always be set to the maximum, regardless of the previous brightness.

The same switch to maximum brightness happens when I try to change the brightness using the Fn key. It goes to max and stays there. Subsequent uses of the Fn key will have no effect.

I tried acpi_backlight and acpi_osi kernel parameters.

I appreciate any help to learn:

How I can fix the Fn key brightness control.
How I can prevent the display switching to maximum brightness instead of its previous brightness.

Last edited by Markus00000 (2013-04-17 13:37:09)

jasonwryan · 2013-04-17 09:20:50

Have you searched the boards for one of the (many other) threads about this issue?

Markus00000 · 2013-04-17 10:12:01

I've added some bits of relevant information to my post, very sorry that I forgot those at first.

Yes, I had searched before and I've gone through the seemingly relevant ones again:

Someone whose problem just disappeared here
A kernel bug for 3.4.x - 3.6.x. On Arch I have 3.8.7, on openSUSE where it works I have 3.7.10. here
An NVIDIA bug. I have Intel HD Graphics 3000 here
Someone who tinkered with WMI drivers which admittedly scared me a bit. here
Issue solved with kernel parameters. I noticed one variant I haven't tried yet, I'll try that in a moment. here and here
Workaround using "echo". here

Some threads about ThinkPads which mention an acpi module for ThinkPads, or where a scancode is available, or where xbacklight also doesn't work.

I failed at finding a thread that matches my situation closely.

Last edited by Markus00000 (2013-04-17 10:16:27)

Markus00000 · 2013-04-17 13:36:31

Solved.

I went through the suggested kernel parameters again and my assumption is that I made a syntax error the last time I tried them.

As I'm using rEFInd I added the following snippet to the options in /boot/efi/EFI/arch/refind_linux.conf:

""acpi_osi=!Windows 2012""

The double quotes seem to do the trick.

nomorewindows · 2013-04-17 14:03:59

Try xev and hit the buttons to see if it even acknowledges those key presses.

Markus00000 · 2013-04-17 15:30:58

nomorewindows wrote:

Try xev and hit the buttons to see if it even acknowledges those key presses.

It doesn't, but that's expected. My understanding is that Fn keys are usually very low level functions which xev cannot catch. Also, my problem was brightness control, the Fn key did work for other functions.

Arch Linux

#1 2013-04-17 08:52:28

[SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

#2 2013-04-17 09:20:50

Re: [SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

#3 2013-04-17 10:12:01

Re: [SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

#4 2013-04-17 13:36:31

Re: [SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

#5 2013-04-17 14:03:59

Re: [SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

#6 2013-04-17 15:30:58

Re: [SOLVED] Fn key brightness control not working on Arch (Dell Latitude)

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