Hardware-level screen brightness control

Hardware Librem 13/15
1

I have a Librem 13 Version 2, and I’m playing around with Liam Proven’s Github project for booting from a USB key into a SvarDOS distraction-free writing environment; it works just fine.

But, when booting that way, I bypass PureOS, and the Fn-F5 and Fn-F6 function keys no longer work to decrease or increase screen brightness, and the computer defaults, it seems, to maximum brightness, which is hurting my eyes.

On other brands of computers, you can often access the BIOS and turn down the screen brightness there, but in SeaBIOS, there seem to be no options except choosing the boot device.

Does anyone know of a way to lower the screen brightness at a hardware level?

Many thanks!

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2

Have you updated Coreboot to the latest release?

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3

I haven’t. Is a later version known to address this problem?

I have SeaBIOS version rel-1.10.0-40-g5bfe90e.

Thank you!

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4

I do not know, but I suggest doing so anyways to see if it resolves your issue:

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5

Isn’t this handled via ACPI tables? Those are constructed during coreboot ramstage and then passed on to the payload. I don’t think old DOS knows anything about ACPI and the environment you mention appears to be just that…

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