Thanks for the animation. I think that flicker is occurring in the LCD itself. The reason is that the old gradient (which was only used in Ubuntu 18.10) covers more colours than 24-bit RGB can support. On top of that, if your monitor is only 18-bit RGB in hardware then you will see even fewer colours and the display/kernel will flicker on purpose to create the illusion of all the shades it can't really display. This is called temporal dithering, or Frame Rate Control:
https://en.wikipedia.org/wiki/Frame_rate_control Essentially that gradient is just a pathological case which will make the shimmering/flickering more visible than it usually is. For this and other reasons, I reported a bug 1789355 too. In the end this is a hardware limitation. But it is a common one which the kernel driver should have some control over. You should be able to configure the nouveau kernel driver directly using something like: xrandr --output DVI-I-1 --set "dithering mode" "off" or xrandr --output DVI-I-1 --set "dithering mode" "static 2x2" based on your Xrandr.txt which says: dithering depth: auto supported: auto, 6 bpc, 8 bpc dithering mode: auto supported: auto, off, static 2x2, dynamic 2x2 I am going to reassign this bug to the kernel because it sounds like the only software solution possible here would be for the kernel to automatically choose a less annoying dithering mode for this model of monitor. P.S. The gradient is completely gone in Ubuntu 19.04 so you won't have any trouble there. ** Package changed: xorg-server (Ubuntu) => linux (Ubuntu) -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1819023 Title: [nouveau] Scrolling screen flicker, especially on default Ubuntu lock screen Status in linux package in Ubuntu: Confirmed Bug description: My screen is experiencing a weird "scrolling" flicker, especially while displaying blue, indigo, and violet hues/colors, such as on the default Ubuntu 18.10 (x64 Desktop) lock screen. The screen flicker scrolls up and down, with the brightest part of the flicker being towards the top, with a gradient that fades back to the original color near the bottom. Problem occurs on any one monitor on any one video output protocol (DVI-D, HDMI, and VGA). I will upload an illustration or render as soon as possible for better explanation. ProblemType: Bug DistroRelease: Ubuntu 18.10 Package: xorg 1:7.7+19ubuntu8 ProcVersionSignature: Ubuntu 4.18.0-16.17-generic 4.18.20 Uname: Linux 4.18.0-16-generic x86_64 ApportVersion: 2.20.10-0ubuntu13.2 Architecture: amd64 BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log' CompositorRunning: None CurrentDesktop: ubuntu:GNOME Date: Thu Mar 7 10:39:50 2019 DistUpgraded: 2018-10-19 10:50:54,557 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process “./xorg_fix_proprietary.py” (No such file or directory) (8)) DistroCodename: cosmic DistroVariant: ubuntu ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: NVIDIA Corporation GF108 [GeForce GT 440] [10de:0de0] (rev a1) (prog-if 00 [VGA controller]) Subsystem: NVIDIA Corporation GF108 [GeForce GT 440] [10de:0828] InstallationDate: Installed on 2018-08-17 (202 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) MachineType: BIOSTAR Group A880G+ ProcEnviron: PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.18.0-16-generic root=UUID=a967adb1-1600-455b-8704-e2bf5de5081d ro quiet splash vt.handoff=1 SourcePackage: xorg UpgradeStatus: Upgraded to cosmic on 2018-10-19 (139 days ago) dmi.bios.date: 09/21/2011 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 080016 dmi.board.asset.tag: To Be Filled By O.E.M. dmi.board.name: A880G+ dmi.board.vendor: BIOSTAR Group dmi.chassis.asset.tag: None dmi.chassis.type: 3 dmi.chassis.vendor: BIOSTAR Group dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr080016:bd09/21/2011:svnBIOSTARGroup:pnA880G+:pvr:rvnBIOSTARGroup:rnA880G+:rvr:cvnBIOSTARGroup:ct3:cvr: dmi.product.family: To Be Filled By O.E.M. dmi.product.name: A880G+ dmi.product.sku: To Be Filled By O.E.M. dmi.sys.vendor: BIOSTAR Group version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.95-1 version.libgl1-mesa-dri: libgl1-mesa-dri 18.2.2-0ubuntu1 version.libgl1-mesa-glx: libgl1-mesa-glx 18.2.2-0ubuntu1 version.xserver-xorg-core: xserver-xorg-core 2:1.20.1-3ubuntu2.1 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.1.0-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1ubuntu1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1819023/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
