Since Linux 6.15, screen brightness on Plymouth decrypt is very low

Framework Laptop 13 Linux
1

OS: Arch Linux
Updated: To 13th of June, 2025
Kernel: 6.15.2
BIOS: 3.09
Model: Framework 13, Ryzen 5 7640

Hi there, I use Arch Linux with Plymouth and the sd-encrypt hook to write the disk passphrase on boot.

I’m not sure what has changes on 6.15, but since then, the screen brightness is very low during all that process, including the passphrase input step. After that while loading the desktop, brightness goes up, probably to what it was set on the Gnome desktop.

I’ve got a second Lenovo laptop with exact same installed software, and it’s not happening there. Not sure if something has changed regarding the screen brightness on 6.15.

3 Likes
2

I doubt this has anything to do with Framework hardware (maybe?), but I just noticed the same thing. I’ve been connected to a dock since that kernel update and just disconnected and rebooted for the first time, noticing the dimming.

3

I see the same with a Ryzen AI-based Framework Laptop and Debian 13 running kernel 6.16.0.

4

I have the same issue on AI 300 and I believe it has nothing to do with Plymouth per se. I’ve noticed that brightness levels are just way off. On 6.14 0%-5% brightness are actually noticeable. On 6.15 levels within 5% to 25% are almost indistinguishable and very low. I am forced to raise it to almost 35% to get equal brightness level to 10% in 6.14

5

There is a fix for this on the mailing list. It didn’t make 6.16 final but it will be in 6.17-rc2 most likely.

You can pull the fix earlier if you want.

4 Likes
6

Thanks a lot!

Is this coming on 6.16 as a bugfix at some point?

7

I had mentioned something in one of my previous posts that when plugged into a power source, the brightness levels were fine. Only when unplugged was the screen very dim at encryption passphrase. Glad to see a fix on the way.

8

Yeah. It should go back to stable eventually. Cherry pick it now if you’re annoyed.