I used the acpi_osi= trick to make Xubuntu 14.04 work with my newly acquired CF-52 Mk 1 Toughbook. Among other things, this enabled it to control the LCD backlight brightness. This mostly works fine, but at 50%, the backlight brightness stops increasing.

These laptops are notorious for failing CCFL backlights. However, I am not experiencing flaring/flashing on startup, dimming over time, or inconsistent brightness. Is it possible that I have either limited the brightness to 50% somewhere without realizing it?


1 Answer 1


Download xblacklight from Ubuntu software store.

Xbacklight is used to adjust the backlight brightness where supported. It finds all outputs on the X server supporting backlight brightness control and changes them all in the same way.

   -get   Print out the current backlight brightness of each  output  with
          such a control. The brightness is represented as a percentage of
          the maximum brightness supported.

   -set percent
          Sets each backlight brightness to the specified level.

   -inc percent
          Increases brightness by the specified amount.

   -dec percent
          Decreases brightness by the specified amount.

   -help  Print out a summary of the usage and exit.

   -time milliseconds
          Length of time to spend fading the backlight between old and new
          value.  Default is 200.

   -steps number
          Number of steps to take while fading. Default is 20.
  • XBackLight produces no change between 50.0% and 75.0% or 100.0%, just like the Fn-key or GUI controls. Mar 4, 2016 at 3:52
  • Are you on Ubuntu or Xubuntu? Mar 4, 2016 at 4:55
  • Xubuntu, as stated in my question. Mar 4, 2016 at 15:37
  • Are you on the latest version? I opened up my terminal and used commands with xbacklight and it worked for me. Did you install xbacklight from terminal or the USC? Mar 4, 2016 at 18:47
  • Have you tried this: 1. sudo nano /etc/rc.local 2. add this line to the file (substitute X with the desired level of brightness): echo X > /sys/class/backlight/intel_backlight/brightness Mar 4, 2016 at 18:49

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