I can't adjust screen brightness of my laptop anymore

Question

My laptop has keyboard buttons for adjusting screen brightness. After a Debian Squeeze re-installation, they don't work no more.

[laptop] Acer TravelMate 6592; I use Fn< to decrease the brightness and Fn> to increase it.

These things can sometimes be brand/model specific so a bit of information about the laptop in question might be useful. — Steven D, Feb 10 '11 at 17:42

score 2 · Answer 1 · edited Feb 11 '11 at 19:35

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Is it a problem of key mapping or a problem of acpi support ?

Check in /proc/acpi/ if you have some entries like this one : /proc/acpi/video/GFX0/LCDD/brightness

If you find it, try to set a value maybe like this :

echo "4" > /proc/acpi/video/GFX0/LCDD/brightness

edited Feb 11 '11 at 19:35

wag

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answered Feb 11 '11 at 19:19

profy

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I don't have the "**/prc/acpi/video**" directory. My kernel is **2.6.32** on Debian. – tshepang Feb 24 '11 at 13:12
What distro do you use? – tshepang Feb 24 '11 at 13:18
I use Ubuntu, but with a kernel on my own (2.6.37). – profy Feb 25 '11 at 20:23

score 1 · Accepted Answer · answered Apr 10 '11 at 11:22

It's probably the case that it got removed in the latest Debian Squeeze kernel (which is where the problem was), and it's now put back in 2.6.38. I say that because it was working way before Squeeze was released (and I only use pristine Debian kernel packages).

score 1 · Answer 3 · edited Apr 13 '17 at 12:22

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If you can change your brightness with root user by typing:

echo 100 > /sys/class/backlight/<xxx>/brightnes

Then, you can follow this link: https://askubuntu.com/a/82320/301773

edited Apr 13 '17 at 12:22

Community

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answered Jul 09 '14 at 04:30

user74909

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For example /sys/class/backlight/intel_backlight/brightness for thinkpads – holms Mar 18 '20 at 01:07

score 1 · Answer 4 · answered Feb 11 '11 at 21:59

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Add "acpi_osi=Linux" to loader

Example:

title Arch Linux
root (hd0,1)
kernel /vmlinuz26 root=/dev/sda5 ro acpi_osi=Linux
initrd /kernel26.img

answered Feb 11 '11 at 21:59

1vanu4

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What is `loader`? – tshepang Feb 24 '11 at 13:15
I've tried this, and I'm, still sitting with the problem. – tshepang Feb 24 '11 at 15:34
It's a /boot/grub/menu.lst – 1vanu4 Feb 27 '11 at 22:48
In my situation it helped me. – 1vanu4 Feb 27 '11 at 22:49
SO you can now adjust brightness using special laptop shortcuts, as in my case? – tshepang Mar 25 '11 at 20:59
Yes. I use "Fn"+ "key arrows" – 1vanu4 Apr 06 '11 at 11:40

I can't adjust screen brightness of my laptop anymore

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