How to control Brightness for Flat Panels?

Timothy A. Seufert tas at
Mon Nov 19 08:28:57 EST 2001

At 12:50 PM -0500 11/18/01, Kevin B. Hendricks wrote:
>How do we go about controlling "brightness" for Flat Panels?  Is this
>functionality in the radeonfb.c or the XFree86 code?
>The new Apple FlatPanels has no manual brightness knob or control so it
>must be done in software.
>Ideas anyone?

For Apple's monitors this might actually happen through USB.  ADC has
it, and it would be a handy data path to use for such commands.  The
fact that MacOS 9 has a "USBAppleMonitorModule" extension and MacOS X
has "AppleUSBDisplays.kext" is suggestive.

If it is in fact USB, you could probably write a userspace program
(using libusb) without touching XFree86 or radeonfb at all.  The
tough part would be deciphering the protocol.  (Pretty easy if you
have a USB protocol analyzer to watch what MacOS does.)
Tim Seufert

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