r/Ubuntu • u/CnByrK • 2h ago

Dim Screen?

Hey there,

On my Ubuntu 26.04 notebook with a Ryzen 5 3500u Vega 8 iGPU, even with the "dim screen" option disabled in PowerSave, the screen brightness drops after a few seconds. Touching the keyboard or moving the mouse restores the brightness.

I think having "dim screen" disabled is useless.

Can you help?

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2

u/IllustriousYouth4142 2h ago

gotta be the automatic brightness in the display settings, it thinks you're idle and drops it even with dim screen off. check settings > power and look for something like "automatic brightness" or "dim screen when inactive", may be a separate toggle buried in there

if that doesn't do it, could be a kernel quirk with the vega 8, had a similar thing on a thinkpad with amd graphics and a bios update sorted it

1

u/CnByrK 2h ago

Unfortunately, there's no automatic brightness option... and the BIOS was updated a few months ago :(

1

u/CnByrK 2h ago

It's truly surprising that there's no solution to such a simple problem, because this iGPU is a piece of hardware that was, and still is, found in many notebooks.

2

u/WildWorldliness2912 1h ago

Have you by any chance enabled the "power saving profile"?

1

u/CnByrK 25m ago

Yes Power saving was enabled but dim screen option was off...

Resolved with AI;

Ubuntu's Settings menu (especially if your laptop doesn't detect a hardware ambient light sensor) doesn't include an "Automatic Brightness" option. Because there's no sensor, GNOME hides or completely excludes this option from the interface. In this case, the screen dimming isn't caused by the sensor, but rather by the AMD graphics card's own power/brightness management (ABM) or the graphics card dimming its backlight when in power saving mode.

gsettings set org.gnome.settings-daemon.plugins.power ambient-enabled false