Created attachment 219854 [details]
For those of us that run -current and can't control the brightness with sysctl.
tested on a dell e6430s with intel card
Works on my Lenovo Thinkpad T490. When changing brightness pressing hotkeys it switches to maximum for a fraction of second and then switches to expected value. When using slider on widget all works fine.
Feel free to commit this with appropriate handling of supported versions. It would also be great if you could start upstreaming the change.