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[SOLVED]Can't adjust screen brightness with keys

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ellescer
Posts: 3
Joined: 2017-05-24 05:15

[SOLVED]Can't adjust screen brightness with keys

#1 Post by ellescer »

I'm running Debian 8.8 on my Acer Aspire Timeline X and I can't seem to adjust the screen brightness with the normal keys.
It would usually adjust with the 'Fn' key and the arrows '< >'. When I do this, I get the pop up with the slider adjusting, but the actual screen brightness isn't changing.

I can actually go into the files:
/sys/class/backlight/intel_backlight/brightness
and adjust it from there on leafpad.
Why don't the buttons work?
Last edited by ellescer on 2017-05-25 02:23, edited 1 time in total.

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orythem27
Posts: 252
Joined: 2017-05-11 07:59
Location: P.R. China

Re: Can't adjust screen brightness with keys

#2 Post by orythem27 »

ellescer wrote:I can actually go into the files:
/sys/class/backlight/intel_backlight/brightness
and adjust it from there on leafpad.
What desktop environment are you using? Are there any other interface folder in /sys/class/backlight/ other than intel_backlight?

If you are using GNOME and there are indeed other interface folder in /sys/class/backlight/, such as acpi_video0,it might be that G-S-D is trying to adjust the wrong interface since it has the following preference:

firmware(acpi_video0) -> platform(acer_wmi) -> raw(intel)

In this case, you might try tweaking related kernel parameters to try to make one of the interfaces to disappear. Relevant kernel params are:

acpi_backlight=vendor
acpi_osi=Linux
acpi_osi=
acpi_backlight=vendor acpi_osi=Linux
acpi_backlight=vendor acpi_osi=
acpi_backlight=intel
acpi_backlight=intel acpi_osi=
acpi_backlight=intel acpi_osi=Linux
... ...
(other possible settings or combinations)

If the above does not work, you can try other common workarounds such as dropping configuration in xorg.conf as described in https://askubuntu.com/a/841903

ellescer
Posts: 3
Joined: 2017-05-24 05:15

Re: Can't adjust screen brightness with keys

#3 Post by ellescer »

orythem27 wrote:What desktop environment are you using? Are there any other interface folder in /sys/class/backlight/ other than intel_backlight?

If you are using GNOME and there are indeed other interface folder in /sys/class/backlight/, such as acpi_video0,it might be that G-S-D is trying to adjust the wrong interface since it has the following preference:

firmware(acpi_video0) -> platform(acer_wmi) -> raw(intel)
I am using Xfce, and there actually is another interface folder in their, "acpi_video0".

How would I go about accessing those kernel parameters?

User avatar
orythem27
Posts: 252
Joined: 2017-05-11 07:59
Location: P.R. China

Re: Can't adjust screen brightness with keys

#4 Post by orythem27 »

ellescer wrote:I am using Xfce, and there actually is another interface folder in their, "acpi_video0".
Then you may first try something like "acpi_backlight=none".
ellescer wrote:How would I go about accessing those kernel parameters?
Edit /etc/default/grub and add kernel params in GRUB_CMDLINE_LINUX_DEFAULT. e.g.

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="splash acpi_backlight=none"
Save and execute `update-grub` before rebooting.

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phenest
Posts: 1702
Joined: 2010-03-09 09:38
Location: The Matrix

Re: Can't adjust screen brightness with keys

#5 Post by phenest »

Different computer but, I use:

Code: Select all

acpi_backight=video
ASRock H77 Pro4-M i7 3770K - 32GB RAM - Pioneer BDR-209D

ellescer
Posts: 3
Joined: 2017-05-24 05:15

Re: Can't adjust screen brightness with keys

#6 Post by ellescer »

orythem27 wrote:Edit /etc/default/grub and add kernel params in GRUB_CMDLINE_LINUX_DEFAULT. e.g.
There's one that has this:

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="quiet"
I will try those parameters you've given me.



EDIT: Yes! I finally got it to work by doing

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=vendor"
Thanks guys, I've learned so much today. :D

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