Unable to physically change brightness | Google Pixelbook (2017) | Arch Linux

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1

For some background information, I am dual booting Chrome OS and Arch Linux on my Google Pixel book EVE 2017. Everything physically works fine in ChromeOS as to be expected, and I resolved almost every issue on the Linux side except for brightness control.

I am running Hyprland and I binded the brightness control keys to change the brightness levels and I can observe the brightness value change in xrandr as well as xbacklight and other programs. So I know that I am changing the value but the problem is that the actual screen is not dimming. It is stuck at the same brightness level unless I set the brightness value to 0, but in that case the screen just turns off.

So I can only have full brightness or a turned off display.

I have tried GitHub - EmbeddedAndroid/linux-eve: Linux Support for the Eve Chromebook (Pixelbook i7)
as well as including i915.enable_dpcd_backlight=1 to the kernal. None of these have fixed the issue.

I have installed vaapi drivers and tried as many solutions as I could find on reddit, google, and forum posts but nothing has seemed to work.

I would appreciate any help or new directions to take to help fix this issue.

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Did you try GNOME or KDE to see if the problem is with the Chromebook and not the DE?

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Hey, thanks for commenting. Yes I did test it out in KDE Plasma, the slider did not change anything and once set to 0, it turns off the display. The keyboard backlight slider worked perfectly though. Tried X11 and Wayland

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the VBT (video bios tables) in the stock firmware, which tell the OS what type of backlight control is used, is incorrect for EVE in the stock firmware, so the OS will never detect it correctly. The stock firmware sets the backlight control type to PWM, but the correct setting is VESA eDP/AUX. You can probably override this somehow, kernel command line perhaps

MrChromebox Full ROM firmware does not have this issue as it uses a corrected VBT.

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That makes a lot of sense actually. This is probably the issue, I will try to figure out how to override it before changing firmwares. A very solid lead

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not probably, is the issue

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