How do I manually turn on the light

James Cobban webmaster at
Wed Feb 13 21:19:41 PST 2013

Alex Deucher wrote:

    In most cases the driver is able to resume fine and bring back the
    backlight.  In your case it doesn't seem to be working.  You might try
    a newer kernel.  I fixed some backlight issues in either 3.6 or 3.7

I really do not believe that this is a problem with the driver or the 
kernel.  The light turns on correctly when I reboot the system. It is 
only when I close and then open the lid of the laptop that the light 
does not come on.  That exact same behavior is displayed when the system 
is configured to use the fglrx driver but the aticonfig --initial script 
has not been run.  Clearly the aticonfig --initial script does not 
change the kernel or the driver, it just alters some scripts.  So 
logically the problem is that some  command is not being issued as a 
result of the lid being opened when I configure the Xorg driver.  I need 
to run the Xorg driver equivalent of the aticonfig script, but I do not 
know what it is!  If I ask Ubuntu 12.10 to activate the Xorg driver 
there is no aticonfig script to run.

>     I do not know what I am doing, so just tell me what to try.

    As I said, normally, it should just work.  You can try adjusting the
    backlight manually with sysfs.

    To check the max brightness:

    To set a brightness level:
    echo [brightness] | sudo tee -/sys/class/backlight/[driver]/brightness
    replace [brightness] with whatever level you want to set and replace
    [driver] with the name of the backlight device on your system.  You
    may have more than one so try all of them.  E.g.,
    /sys/class/backlight/radeon/, etc.

/sys/class/backlight/ only contains one sub-directory acpi_video0, in 
which the brightness and max_brightness files both contain 15.  I do no 
believe that the problem is with the brightness of the display the 
problem is that the light is OFF!  Admittedly at this moment I am 
running with the fglrx driver because whatever the aticonfig --initial 
command sets up correctly instructs that driver to turn the light on, so 
I do not know for a fact what is in /sys/class/backlight when the Xorg 
driver is installed.

Jim Cobban webmaster at 
<mailto:webmaster at>
Web-site: <>
34 Palomino Dr.
Kanata, ON, CANADA
K2M 1M1
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