SteamOS brightness control for Legion Go 2 is almost there...
Hey guys!
I want to share some good news with you. I believe we will soon be finally able to properly control brightness on official SteamOS. I'm a software engineer myself, so there are some technical details.
In Game Mode, the screen is always in PQ-based HDR mode. A silent hero, Lorenzo Morelli, found a way to control the brightness of SDR content in "gamescope session" and made a public LegionBetterSpace program for Linux, which contains brightness-bridge script. I believe that's the same way KDE Plasma works.
The default (currently static) value is 200 nits. This script allows changing brightness from 5 up to 500 nits. The theoretical maximum should be 1107 nits, yet probably not the best idea to go that high for SDR.
The way it works is different from well-known Decky plugin or custom lua file, which switches from bright PQ-curve to a dim Gamma2.2 mode.
More info:
https://github.com/ValveSoftware/gamescope/issues/2172#issuecomment-4492199487
According to my own tests, this works really well. If you spread the word for higher visibility, other distros (e.g., Bazzite) can already start including it.