ISSUE: Backlight brightness does not change.
More Detail: Brightness will not change, using both 'System Settings->Screen', or Fn keys (Brightness bar shows and moves, but screen brightness does not change).
Noticed a post about having multiple folders in Sys->Class->Backlight. I HAVE TWO FOLDERS TOO: intel_backlight and acpi_video0.
Using the function keys, alters the value in the acpi_video0's 'Brightness' file – But doesn't actually alter the brightness of the screen.
If I add backlight=vendor in Grub, my function keys then edit the value in the Intel_Backlight brightness file. – But again doesn't actually change the brightness of the screen.
Computer: Fujitsu Siemans Pi2515, Intel Integrated Graphics, No HDD partition.
Already Tried:
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Editing grub to contain:
acpi_osi=Linux acpi_backlight=vendor -
http://ubuntuguide.net/change-screen-brightness-with-fn-key-in-ubuntu-11-0410-10
sudo apt-get install acpi sudo setpci -s 00:02.0 F4.B=20 -
Brightness does not adjust in fallback mode either.
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Reinstalling OS, Using Linux Mint (Same problem).
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Upgrading and downgrading BIOS.
Many thanks for reading, I understand this problem may need a bit of a Linux pro to sort. If anyone up for the challenge I'll spend any amount of time being walked through this, posting results. Don't want to give up here!
Best Answer
I have a very similar problem with a Toshiba Portege R935 in 12.04. I can't change the brightness after suspending and resuming.
The Grub line didn't help either (actually with that line, it stopped working even before suspending).
In the meantime, I discovered this workaround:
as root, change the value in
sys/class/backlight/intel_backlight/brightness. for instance:Warning: these values are not between
0and7(as the ones in the other directory), but between284and4539, or something like that.