Sebastian WickAug 8, 2025

Over the last year, I overhauled the screen brightness handling in GNOME! This will become available in the upcoming 49 release, but you can already try it on GNOME OS.

https://blog.sebastianwick.net/posts/gnome-49-backlight-changes/

GNOME 49 Backlight Changes

One of the things I’m working on at Red Hat is HDR support. HDR is inherently linked to luminance (brightness, but ignoring human perception) which makes it an important parameter for us that we would like to be in control of. One reason is rather stupid. Most external HDR displays refuse to let the user control the luminance in their on-screen-display (OSD) if the display is in HDR mode. Why? Good question. Read my previous blog post.

swick's blog
Show threadngz0
@swick in 49 on my laptop brightness can't be changed when in HDR. Is it expected for now?
Aug 9, 2025 at 5:03amMastodon for Android
Show threadSebastian WickAug 15, 2025
@ngz0 The problem with integrated panels is that they often offer sysfs backlights which then simply stop having any effect in HDR mode. If they were exposed via KMS instead we could notice that they are not usable after a mode set into HDR. A patch just got merged which always uses the "software" backlight for now. Unfortunately a side-effect of that is that if you had working driver/hardware level backlight control in HDR mode, you're now stuck with the "software" backlight.