[Dell XPS 15 9575] Screen brightness stopped working with linux-image-5.4.0-9-generic

[Mario Vukelic]

I upgraded to Focal Fossa 3 days ago and nothing broke. At the time, it was still using linux 5.3 (linux-image-5.3.0-24-generic).

Today, it updated to linux 5.4 (linux-image-5.4.0-9-generic) and after rebooting, the screen brightness does not work anymore - neither from keyboard keys nor from the slider in the gnome-shell panel.

It works again when rebooting into the previous linux-image-5.3.0-24-generic kernel.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-9-generic 5.4.0-9.12
ProcVersionSignature: Ubuntu 5.4.0-9.12-generic 5.4.3
Uname: Linux 5.4.0-9-generic x86_64
ApportVersion: 2.20.11-0ubuntu15
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: mario 1892 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Wed Jan 8 20:23:31 2020
InstallationDate: Installed on 2018-09-13 (481 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Alpha amd64 (20180912)
MachineType: Dell Inc. XPS 15 9575
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-9-generic root=UUID=26ff4c95-5f68-4121-b7d0-989fa705fcc8 ro quiet splash
RelatedPackageVersions:
 linux-restricted-modules-5.4.0-9-generic N/A
 linux-backports-modules-5.4.0-9-generic N/A
 linux-firmware 1.184
SourcePackage: linux
UpgradeStatus: Upgraded to focal on 2020-01-04 (3 days ago)
dmi.bios.date: 07/07/2019
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.7.1
dmi.board.name: 0C32VW
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 31
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.7.1:bd07/07/2019:svnDellInc.:pnXPS159575:pvr:rvnDellInc.:rn0C32VW:rvrA00:cvnDellInc.:ct31:cvr:
dmi.product.family: XPS
dmi.product.name: XPS 15 9575
dmi.product.sku: 080D
dmi.sys.vendor: Dell Inc.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Kai-Heng Feng (kaihengfeng)]

Please test latest mainline kernel:
https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.5-rc5

[Mario Vukelic (kreuzsakra)]

Yes, this works again

[Pat Viafore (patviafore)]

For those looking for a workaround in the meantime, I've found that lxqt-config-brightness -i and lxqt-config-brightness -d on the command line are still able to control the screen brightness in my setup.

[Mario Vukelic (kreuzsakra)]

Still occurs with linux-image-5.4.0-12-generic
Now that apparently it was decided that Ubuntu 20.04 will use linux 5.4, it would be nice to fix it in 5.4 as well :)

[Olivier P (olivierp)]

Same issue on a Dell XPS 13 9370.

Still occurs with linux-image-5.4.0-14-generic.

[Kyle Weber (kyew01)]

Same here on a XPS 13 7390, 5.4.0-14-generic also.

[Maximilian Federle (ppd)]

Also failing on Dell XPS 13 9370, 5.4.0-17-generic

[Kai-Heng Feng (kaihengfeng)]

Same as #1864698?

[AceLan Kao (acelankao)]

Here is a new test kernel which not only revert the quirk, but introduce a new way to quirk the panels which support DPCD backlight
https://people.canonical.com/~acelan/bugs/lp1861521/

[Olivier P (olivierp)]

Thanks , this test kernel fixes the issue with my XPS 9370 .

[Mario Vukelic (kreuzsakra)]

OP here, test kernel works for me too

[Mario Vukelic (kreuzsakra)]

As per prev. comment, the test kernel re-enables the keyboard brightness setting. However, the slider in the Gnome panel menu is not being moved when using the keyboard keys. Dragging the slider with the mouse does change the brightness, though.

(May be related: The volume slider in the panel menu & the volume keys show the same behaviour: the volume keys work but do not affect the slider)

And by the way, the brightness problem also occurs on Asus Zenbook Flip UX561UD, and the test kernel behaves in the same way, keys work but slider unaffected.

[Sergei Beilin (saabeilin)]

Dell Precision 5540, Linux liberty 5.4.0-14-generic #17-Ubuntu SMP Thu Feb 6 22:47:59 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

- brightness keys do not work
- brigttness control from Xfce power applet does not work
- `xrandr --output eDP-1 --brightness 0.5` works unless `redshift` is running

[Antti Salmela (asalmela)]

Upgrade to 5.4.0-18-generic fixed this for me.

[Mario Vukelic (kreuzsakra)]

5.4.0-18-generic fixed it for me too (OP, Dell XPS 15 9575) as far as the keyboard keys are concerned. The slider in the gnome panel however is still not moved when I use the keyboard keys.

[Olivier P (olivierp)]

5.4.0-18-generic fixed it for me too (Dell XPS 13 9370) . Thanks !

[Mario Vukelic (kreuzsakra)]

The issue with the brightness slider not moving in the gnome panel menu, in response to brightness keys, was fixed after the latest round of updates that installed gnome-shell 3.36.
So all is good now on the Dell XPS 9575, thank you!

[Po-Hsu Lin (cypressyew)]

Closing this bug as per Mario's response in comment #19