Arch Linux

Niourf

Member

Registered: 2014-03-18

Posts: 13

Backlight control using acpi keys : works fine, but don't know why!

Hi guys,

I use acpid to manage acpi events on my laptop (Asus X53S). I have configured the keys for sound management, and it works perfectly fine.
One thing puzzles me though: I am also able to control the screen brightness using acpi keys, even if there is nothing related to blacklight in /etc/acpi/.

I checked, and I haven't installed any of the backlight utilities mentioned here https://wiki.archlinux.org/index.php/ba … _utilities. I use awesome v3.5.2 and there is nothing either in my rc.lua file.

Where could it come from then?

Thanks!
Nicolas

easysid

Member

From: India

Registered: 2013-01-01

Posts: 256

Re: Backlight control using acpi keys : works fine, but don't know why!

do you have a power manager running? like xfce4-power-manager, because they can handle brightness keys

Last edited by easysid (2014-04-01 15:58:04)

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Niourf

Member

Registered: 2014-03-18

Posts: 13

Re: Backlight control using acpi keys : works fine, but don't know why!

Hey, thanks for helping.

I do have laptop-mode-tools installed. I configured it to automatically set the screen brightness, depending on whether my battery is plugged or not, but there is nothing related to ACPI keys as far as I know.

Last edited by Niourf (2014-04-01 16:24:03)

brebs

Member

Registered: 2007-04-03

Posts: 3,742

Re: Backlight control using acpi keys : works fine, but don't know why!

Run xev, to check - the key is probably being recognized as XF86MonBrightnessUp etc.

Niourf

Member

Registered: 2014-03-18

Posts: 13

Re: Backlight control using acpi keys : works fine, but don't know why!

It is a bit strange :
They are indeed recognized as XF86MonBrightnessUp and XF86MonBrightnessDown, but only when I use the kernel parameter

video.use_native_backlight=1

However, the kernel parameter I actually use is

acpi_osi=Linux acpi_backlight=vendor

because with the other one,  backlight is automatically set very low when I start X.
And with this parameter, keys are not recognized as X86MonBrightnessXXX.
I can still use the keys to adjust backlight though, regardless of the kernel parameters.

Don't know it that helps, but I appear to have 3 cards to manage backlight :

~ » ls /sys/class/backlight                                                                                                                nico@cotier
acpi_video0  acpi_video1  intel_backlight

My graphic card has the optimus technology so there should only be 2, right?

I am a bit confused...