How to disable low display brightness when power fail?

Roland Smith rsmith at
Tue Feb 4 19:34:26 UTC 2014

On Tue, Feb 04, 2014 at 01:55:13AM -0800, Unga wrote:
> Hi all
> I have a laptop running FreeBSD 9.2 and KDE4. 
> When main A/C power fails, this laptop immediately reduces the display brightness. When power restores, it also immediately restore the full brightness.
> Because of this I cannot show a presentation without power.
> Therefore, how to disable becoming low bright when no main A/C power?
> I prefer a xorg.conf entry.

This is possibly done via a script called by devd when it catches a AC line
state event. In that case there should be a block of commands in either
/etc/devd.conf, or in one of the files in /etc/devd or /usr/local/etc/devd
that looks like this:

# Switch certain settings when the AC line state changes.
notify 10 {
        match "system"          "ACPI";
        match "subsystem"       "ACAD";
        action "/usr/local/etc/rc.d/acstate $notify";

The name of the action and the priority (the number behind "notify") can be
different. Commenting-out this block of commands and restarting devd will
inhibit the action.

But it can be that KDE has its own mechanism for doing this. Have a look at
the KDE settings.

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