Intel graphics card brightness control issue

Matthias Petermann matthias at
Wed Sep 4 08:30:54 UTC 2013

Hi Ethan,

Zitat von "Ethan W. House" <ehouse at>:

> What could be causing my brightness control to not work on my Intel
> graphics card. The acpi values change but no effect takes place.
> ehouse at derpy ~ $ sudo sysctl
> 100 -> 50
> ehouse at derpy ~ $ sudo sysctl
> 0 -> 0
> I also have an issue were upon resume by machine reboots. I believe the two
> might be related but I am not sure.
> I found a couple of other email chains with similar issues but most of them
> have been inactive for more then a year.

Which Laptop model do you have? This issue appears a bit familiar to  
me[1] - I have the same on my Thinkpad. As a workaround you could try  
to change the brightness by direct ACPI calls.


* install sysutils/acpi_call
* kldload acpi_call

Change brightness:

* acpi_call -p '\VBRU'   (Brightness Up)
* acpi_call -p '\VBRD'   (Brightness Down)

It might be that these calls are specific to Thinkpads, not sure if  
they work with others. You can try to find out with acpidump[1].

Kind regards,

Matthias Petermann <matthias at>
Ihr Partner für anspruchsvolle IT-Lösungen - lösungsorientiert, innovativ und erfolgreich

More information about the freebsd-questions mailing list