System Details
- Device: 2017 Google Pixelbook i5
- OS: Arch using KDE Plasma 6.7.2 (Wayland via Kwin)
- Firmware Type: RW_LEGACY
- Firmware Version: Most up to date firmware available
- Internal storage type: SSD
Summary of the Issue
The Pixelbook has pretty much full functionality with linux, except for two needed tweaks. Once is a chromebook audio script to run, and the other is backlight.
Adjusting the backlight (using the slider in KDE) does not work without editing your GRUB file and putting in this line: GRUB_CMDLINE_LINUX=“i915.enable_dpcd_backlight=1”
This “fix” has worked with any flavor of linux. I have personally tested in Kubuntu, MX Linux, CachyOS, and now Arch.
The problem now is, something changed with the Linux 7.1 kernel where this doesn’t work anymore. Still works perfectly on 7.0.x kernel and below, but any 7.1 (or 7.2rc kernel) does not work and I’ve tried a million fixes, and nothing works. The million fixes include removing that line, changing the value to 0, 2, or 3.
Tried this, didn’t work: GRUB_CMDLINE_LINUX=“i915.enable_dpcd_backlight=1 i915.enable_psr=0 i915.enable_fbc=0” Also tried GRUB_CMDLINE_LINUX=“acpi_backlight=native”
I have tried the software brightnessctl, making changes with it has no effect. Also tried the software gammastep, doesn’t work. And other ones like “colord” (I think that’s what it is called). NOTHING changes the brightness if using 7.1 or newer kernel.
Steps to Reproduce
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Install RW_LEGACY firmware on Pixelbook and any flavor of Linux with kernel 7.1 or higher.
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Edit GRUB_CMDLINE_LINUX=“i915.enable_dpcd_backlight=1” and update grub. This is the fix for backlight controls that works for kernel 7.0.x and lower.
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With 7.1 kernel or higher, this fix does not work, neither do any other known fixes for controlling backlight.
Expected Behavior
I should be able to use the slider in KDE for backlight/brightness and adjust the brightness, just as I can do with any kernel 7.0.x or lower. I have reached the conclusion that something changed in the 7.1 kernel, but have no idea on how to get this fixed. Or if it is even possible. Perhaps I am stuck just using 7.0.x and below on this device until EOL.
Thank you!!