Framebuffer video for Whiskey Lake Intel 620

Hello from a ThinkPad X1 Carbon running Haiku! Nearly everything woks - sound, trackpoint, wifi, and surprisingly - touchscreen! A few things don’t - touchpad, and unfortunately, display driver is just framebuffer, so I don’t have brightness control.

Any possible hacks to get screen brightness control? A driver in development that anyone knows of?

Devices identifies it as: WhiskeyLake-U GT2 [UHD Graphics 620]

Thank you! Huge Haiku fan - thanks for all this community does!


Hello @ActionRetro and welcome!
A hack I use for brightness in my Thinkpad T450s is something I read somewhere in this forum, long time ago, probably posted by @PulkoMandy : try to set it before boot when you are still in bios/efi mode. In my case I have a bios password set on boot and when it stops there I adjust the brightness. Not the best but it works in my case.

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We already support the vesa way, so if that doesn’t work only the driver proper support would remain. In which case: open a bug that the driver does not support the card.

We don’t support setting brightness “the VESA way”… I attempted it a few years ago but we never found a machine that supports it, and the patch was never merged:

Anyway, this would probably not be helpful on modern hardware where I assume efi is used to boot the system. In that case, in theory it should be possiple to use ACPI to set the brightness in a generic way. My attempt at this was also unsuccessful and not included in current nightly builds:

So, maybe the best thing to do is to add support for this hardware to the Intel graphics driver. It depends how much they changed things compared to previous generations of hardware. This weekend I worked a bit on Tiger Lake support (since that’s the hardware I own) but this will need a bit more time to ma%e it work on machines that are not mine (a couple things are hardcoded for now). Once that is finalized, we can attemht to enable it for newer machines, see what happens, and try to fix it. Unfortunately my experience is it’s already difficult enough to make things work on machines I own, and doing remote debugging is often too time consuming to get things done. I can always try to make a few changes “blindly” (without testing) and if we are a bit lucky, it could get things to work.


Oh, sorry for writing false information, I misremembered and thought it was merged. My bad.

Thinkpad T430s, setting brightness with key before boot works, in haiku the keys do not work, but the brightness slider in settings → display works

No worries, with so many changes waiting in code review, it’s a bit difficult to keep track of what’s already merged or not. We should try to get that list down a bit…