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.
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These things can sometimes be brand/model specific so a bit of information about the laptop in question might be useful.– Steven DFeb 10, 2011 at 17:42
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4 Answers
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
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I don't have the "/prc/acpi/video" directory. My kernel is 2.6.32 on Debian.– tshepangFeb 24, 2011 at 13:12
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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
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SO you can now adjust brightness using special laptop shortcuts, as in my case?– tshepangMar 25, 2011 at 20:59
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).
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
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For example /sys/class/backlight/intel_backlight/brightness for thinkpads– holmsMar 18, 2020 at 1:07