Desktop doesn't remember brightness settings after a reboot

The file /etc/rc.local should look like this:

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
echo 0 > /sys/class/backlight/acpi_video0/brightness
exit 0

Per @zerdo: In my dell studio 1558 the brightness setting is stored in /sys/class/backlight/intel_backlight/brightness. Just change the path if your computer doesn't use the acpi_video0 folder.

Also, per @Nick : If this is the only answer you read, note that the 0 in echo 0 is going to be your default brightness setting. I had set this up and it was driving me crazy for a long time : every time I booted up, it would set it to the lowest brightness setting. I prefer mine to start at max brightness, so I used echo 10 instead. Your hardware might vary in brightness scale.


This function, the backlight control, is dependent on your bios and kernel version.

Try these four things.

Kernel (boot) options

When you boot, at the grub screen, hit e to edit. To the kernel line add nomodeset acpi_backlight=vendor Some hardware may work with different options.

Intel - nomodeset acpi_backlight=intel Acer - acpi_backlight=acer_acpi or even acpi_osi=Linux acpi_backlight=legacy.

As you can see, you may need to google search for your settings.

quiet splash nomodeset acpi_backlight=vendor

If that works, edit /etc/default/grub and add those options to the default options.

# command line
sudo -e /etc/default/grub

# graphical
gksu gedit /etc/default/grub

Edit the "GRUB_CMDLINE_LINUX_DEFAULT" line so it looks like this

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"

Save your edit, update grub

sudo update-grub

Command line

If that does not work, you can try to manually set the brightness.

Note: Path may vary with hardware / kernel version, may be /proc/acpi/video0 ..., you may need to browse the /proc/acpi directory to find the brightness setting and adjust the following commands accordingly.

cat /proc/acpi/video/VGA/LCD/brightness

The output of that command varies a bit with hardware, 1 -> 10 , 1 -> 12 , 1 -> 100 ??? Choose a value and set it (choose the value for your hardware).

sudo echo 80 > /proc/acpi/video/VGA/LCD/brightness

If that works, add it to /etc/rc.local

# command line
sudo -e /etc/rc.local

# graphical
gksu gedit /etc/rc.local

Add in your setting above "exit 0"

echo 80 > /proc/acpi/video/VGA/LCD/brightness

xbacklight

You can also try xbacklight

sudo apt-get install xbacklight

You then adjust with the command line

# For 80 % brightness
xbacklight -set 80

Again, add that to /etc/rc.local

# command line
sudo -e /etc/rc.local

# graphical
gksu gedit /etc/rc.local

Add in, above "exit 0"

xbacklight -set 80

setpci

You can try to set your brightness with setpci

The general syntax is 

sudo setpci -s <address> f4.B=your_setting

You identify your pci bus address with

sudo lspci | grep VGA

Example

00:02.0 VGA compatible controller: Cirrus Logic GD 5446

setpci -s 00:02.0 F4.B=80

If you get your setting wrong, most likely you will just loose your display, and have to reboot. As this is a hardware setting, you really need to identify your hardware and research the settings first.

Examples

Intel - https://bbs.archlinux.org/viewtopic.php?id=74914

Toshiba - http://www.linlap.com/wiki/toshiba+satellite+t130

Acer extensa - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/518002

Ubuntu man page setpci


This is supposed to be configurable in the energy options, set the brightness to the desired level and it will always be used. If you use a laptop you will also need to configure the level for battery mode as well...

I found that Gnome has some issues about lcd panel brightness, e.g. if I run on battery mode and set the brightness manually to a given level and leave the laptop unattended for 10 seconds it will go back to the preset brightness when I take control back. Same goes when on A/C mode except it takes longer so goes unnoticed more easily. I believe all those settings should be saved somewhere and restored - at least for A/C mode.

EDIT: For gnome3 this does not work (at least for me).

Tags:

Gnome

Brightness

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