I use Xubuntu Linux

Brightness is good without using suspend mode but after using suspend mode I got problem with brightness It's lower than before ! I need your help



Some Ubuntu laptops screen brightness reset to the lowest or highest on every boot and you have to configure the screen birghtness on every login.

To save the screen brightness settings in Ubuntu laptop.

Open a terminal window, and execute this command to edit /etc/rc.local:

sudo nano /etc/rc.local

Add this before the last line “exit 0″:

echo 5 > /sys/class/backlight/acpi_video0/brightness

number 5 is the value of your screen brightness. With this command check the maximum:

cat /sys/class/backlight/acpi_video0/max_brightness
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My m6700 use the disk from another PC, which has xubuntu 12.04.

I had the same problem then I downloaded the kernel from


and compiled using the command:

fakeroot make-kpkg --revision 00.m6700 --initrd --append-to-version=-localmod  kernel-image kernel-headers

and then installed the generated packages by the command dpkg -i *.deb, then after a reboot the problem was solved.

The Git branch I checkout out was:

  • Commit 35fd156f210074f981de9963ecd07fb3630e072d
  • Author: Brad Figg
  • Date: Tue Dec 3 08:37:09 2013 -0800
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Try modifying your /etc/default/grub file.

gksudo gedit /etc/default/grub

Edit the line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

To: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Or: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

Then run sudo update-grub and reboot.

Source: https://wiki.ubuntu.com/Kernel/Debugging/Backlight

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