Screen brightness adjustment delay in Xorg sessions only

[phillip]

Every time I adjust my laptop's screen brightness using the dedicated brightness keys, there is a substantial delay between when I press the button and the screen adjusts. Sometimes it even "twitches" and decreasing the brightness by tapping the button two times will quickly drop the brightness all the way to the lowest setting after the delay takes place. I've noticed the issue in the default Ubuntu session and in my current vanilla gnome-session. It also doesn't matter which extensions I have installed. The keys work flawlessly in Windows so it isn't a hardware issue. I have been meaning to report this for a while and have just never gotten around to it until just now.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: xorg 1:7.7+19ubuntu12
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Uname: Linux 5.3.0-19-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: GNOME
Date: Thu Nov 7 14:37:43 2019
DistUpgraded: 2019-10-21 20:16:37,104 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: eoan
DistroVariant: ubuntu
DkmsStatus: nvidia, 435.21, 5.3.0-19-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation UHD Graphics 620 [8086:5917] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Huawei Technologies Co., Ltd. UHD Graphics 620 [19e5:3e04]
   Subsystem: Huawei Technologies Co., Ltd. GP108M [GeForce MX150] [19e5:3e04]
InstallationDate: Installed on 2019-09-08 (59 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 05c8:03c0 Cheng Uei Precision Industry Co., Ltd (Foxlink) HD Camera
 Bus 001 Device 002: ID 8087:0a2b Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: HUAWEI MACH-WX9
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-19-generic root=UUID=75fe2138-1abd-47b2-a73f-83280ff782ff ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to eoan on 2019-10-22 (16 days ago)
dmi.bios.date: 03/15/2019
dmi.bios.vendor: HUAWEI
dmi.bios.version: 1.28
dmi.board.name: MACH-WX9-PCB
dmi.board.vendor: HUAWEI
dmi.board.version: M14
dmi.chassis.type: 10
dmi.chassis.vendor: HUAWEI
dmi.chassis.version: M14
dmi.modalias: dmi:bvnHUAWEI:bvr1.28:bd03/15/2019:svnHUAWEI:pnMACH-WX9:pvrM14:rvnHUAWEI:rnMACH-WX9-PCB:rvrM14:cvnHUAWEI:ct10:cvrM14:
dmi.product.family: MateBook X
dmi.product.name: MACH-WX9
dmi.product.sku: C128
dmi.product.version: M14
dmi.sys.vendor: HUAWEI
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.99-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.1-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 19.2.1-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.20.5+git20191008-0ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.0.1-1ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20190815-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

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

This change was made by a bot.

[Daniel van Vugt (vanvugt)]

Please look in Settings > Power and ensure automatic brightness is not enabled. That could be part of the problem.

[phillip (horkrvkz)]

Automatic brightness not enabled. Also, I have found the issue is not present in Wayland, only during Xorg sessions.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 19.10 (eoan) reached end-of-life on July 17, 2020.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in and change the bug status to Confirmed.