It looks like modesetting, or at least a destructive probe of the attached displays.
There's nothing KMS related in dmesg corresponding to the blanking, so I don't think it's an invalid FB (I'd expect i915 to spit something in dmesg in that case) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/1842009 Title: [Wayland] Screen blanks for a second whenever discrete GPU is powered up Status in gnome-shell package in Ubuntu: New Status in mutter package in Ubuntu: New Bug description: On this Kaby Lake G laptop, GNOME Shell blanks the screen for a second each time the AMD GPU is powered up. Triggers for powering up include: launching something which loads GL such as Steam or glxinfo, loading the Display configuration page, and so on. This behaviour does *not* occur with GNOME Shell under X, so it's probably something to do with mutter's KMS interactions. Because the GPU powers down quite aggressively (I think it's about 5sec without activity) this can be quite annoying :) ProblemType: Bug DistroRelease: Ubuntu 19.10 Package: gnome-shell 3.33.91-1ubuntu1 ProcVersionSignature: Ubuntu 5.1.0+bcachefs.git20190828.bc3a6a71-1-generic 5.1.2 Uname: Linux 5.1.0+bcachefs.git20190828.bc3a6a71-1-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu7 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Fri Aug 30 09:48:25 2019 DisplayManager: gdm3 InstallationDate: Installed on 2019-08-29 (0 days ago) InstallationMedia: Ubuntu 19.10 bcachefs (20190828) RelatedPackageVersions: mutter-common 3.33.91-1ubuntu1 SourcePackage: gnome-shell UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1842009/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
