Bug 451579

Currently external monitor birghtness is not handled. This is a feature request to add software support for external monitors brightness via MCCS. An example program that already does this/might be a good "underpinning" with more information on the spec/communication is ddcutil (https://www.ddcutil.com/).

As an example, I can use the following ddcutil commands to set both monitor's brightness to 100%:

$> sudo ddcutil setvcp -d 1 10 100
$> sudo ddcutil setvcp -d 2 10 100

Or 50%:

$> sudo ddcutil setvcp -d 1 10 50
$> sudo ddcutil setvcp -d 2 10 50

As some extra background as for "why" my office has a lot of light in the morning/when it's snowy outside vs very dark at night, so I regularly need to adjust monitor brightness throughout the day. It's much more convient to do that with software. I think adding keyboard controlled/GUI slider based brightness integration would be a really nice feature for KDE to have for external monitors.

It would be ideal to eventually be able to have some presets, maybe have a "default brightness curve" for the day, etc. However, the first step with any of that would be IMO, exposing basic brightness controls for the monitors.