2017 Pixelbook backlight control doesn't work with 7.1 kernel

pappy97 · July 6, 2026, 4:45pm

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

Install RW_LEGACY firmware on Pixelbook and any flavor of Linux with kernel 7.1 or higher.
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.
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!!

pappy97 · July 8, 2026, 7:43pm

Anyone? I’ve gone ahead and reported a regression to linux kernel devs/maintainers, but I thought perhaps someone here might have a fix beyond this or understand what changed in Linux 7.1.x kernel to cause this, so it can be fixed on our end. If it has to be a kernel dev fix, then so be it. Thanks.

MrChromebox · July 9, 2026, 2:56pm

not sure there are a ton of folks here using this device

matthew · July 21, 2026, 1:57am

There are dozens of us! Or at least two of us.

I’ve found two reddit posts and an Arch posts in addition to this one. All the same poster?

pappy97 · July 22, 2026, 2:01am

Don’t know…are you also having this issue with Kernel 7.1.x or higher?

matthew · July 22, 2026, 2:32am

Yes. I’m running Ultramarine on the Pixelbook and the problem started just before updating to release 44. Unfortunately the backup kernel is also 7.1.x. The recent update to 7.1.4 did not resolve it.

pappy97 · July 22, 2026, 3:11pm

1.) Please report the regression to [email protected]. I think the linux devs seem to think my issue is a one off, but it’s obviously not. It’s still not working on linux mainline 7.2.x either.

2.) They had asked me to run a git bisect to find the offending commit, which I did, shown below. Doesn’t seem like they want to accept that this commit broke the backlight control functionality.

b3793af3277f65d256d67f9949e760b434ff66dd is the first ‘bad’ commit
commit b3793af3277f65d256d67f9949e760b434ff66dd
Merge: 51cc1c427461 88919bedabb8
Author: Jiri Kosina <[email protected]>
Date: Thu Apr 16 21:08:14 2026 +0200

Merge branch ‘for-7.1/intel-thc’ into for-linus

power management improvements to intel-thc-hid driver (Even Xu)

drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c | 16 +++++++++±-----
drivers/hid/intel-thc-hid/intel-thc/intel-thc-dev.c | 47
+++++++++++++++++++++++++++++++++++++++++++++++
drivers/hid/intel-thc-hid/intel-thc/intel-thc-hw.h | 4 ++++
3 files changed, 61 insertions(+), 6 deletions(-)

chrultrabook_enjoyer · July 22, 2026, 4:18pm

Device model: Google Pixelbook 2017 i7 (EVE)
OS: Fedora 44 KDE
Kernel: 7.1.4
Firmware: mrchromebox uefi full rom

I don’t have much to add to this conversation besides a report that I’m experiencing the same issue after a recent system update–adjusting the brightness slider in the KDE ui doesn’t affect the physical display brightness. I’ve tried restarting and updating the system, as well as that trick about updating the line in the grub file, to no avail.

I have a couple of questions if someone is willing to answer:

Do you think this has much to do with mrchromebox firmware or is it most likely a linux issue that just happens to be affecting this device running mrchromebox firmware?
The only options right now are to rollback the kernel to 7.0.x or less according to op, or wait for some kind of fix, is that right?

pappy97 · July 22, 2026, 6:03pm

Please report the regression to [email protected].

As I said above, the linux devs introduced a change into 7.1.x and further that messed this up. I don’t think it’s a firmware issue, it’s literally a linux dev issue (I did the dirty work with the git bisect and found the offending commit FFS!) and they can fix it. We just need everyone with this issue to email [email protected] and report the issue. The more people that report it, the better chance that they will do something about it.

For my temp fix, I’m using the LTS kernel, which is still 6.18.x, so it the backlight control works just fine (with the well known grub edit).

matthew · July 27, 2026, 12:49am

I reported it and they pointed me to this fix that has already been merged for 7.2.x.

I built master on commit 3dab139d4795 and the display brightness is adjusting fine.
The kernel version is reported as 7.2.0-rc4-custom.

pappy97 · July 27, 2026, 4:14pm

This is great news!!

Do you still need your grub file to have this edit GRUB_CMDLINE_LINUX=“i915.enable_dpcd_backlight=1”

Or does it work without it?

matthew · July 27, 2026, 4:33pm

I’ve never needed to have that.

I did add it in when this started with 7.1, but took it out before trying the other kernels.

pappy97 · July 27, 2026, 4:45pm

Strange, because I’ve always needed that ever since I put Linux on Pixelbook in 2023. Thanks.

matthew · July 28, 2026, 3:08am

This is what I have.
The iomem was added recently to allow updates to the mrchromebox UEFI firmware.

GRUB_CMDLINE_LINUX="rhgb quiet pcie_aspm=off iomem=relaxed"

MrChromebox · July 28, 2026, 3:20am

isn’t needed anymore, fixed in firmware a few releases back

pappy97 · July 28, 2026, 4:21pm

Using the latest linux mainline (7.2-rc5), my backlight works again too. But I still had this in my GRUB line:

GRUB_CMDLINE_LINUX=“i915.enable_dpcd_backlight=1”

Don’t know if I need it, but as long as it works, I’m keeping it there.

matthew · September 10, 2026, 12:30pm

The latest Fedora updates included a 7.2 kernel.
I’ve updated to that and the backlight issue is resolved.

Kernel Version: 7.2.4-200.fc44.x86_64 (64-bit)