> The only thing that worked was switching the monitors from DisplayPort to HDMI on the dock.
That's consistent with the kernel error in comment #20 and consistent with comment #12, since MST is a DisplayPort feature. ** Summary changed: - Window manager freezes when plugging in USB-C dock with external monitor. + Window manager freezes when plugging in USB-C dock with external monitor ([drm] *ERROR* mstb 00000000f21f0a30 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed) ** Also affects: linux (Ubuntu) Importance: Undecided Status: New ** Changed in: linux (Ubuntu) Status: New => Confirmed ** No longer affects: gnome-shell (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/1970495 Title: Window manager freezes when plugging in USB-C dock with external monitor ([drm] *ERROR* mstb 00000000f21f0a30 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed) Status in linux package in Ubuntu: Confirmed Status in mutter package in Ubuntu: Confirmed Bug description: 1. Problem DOES appear on Lenovo T470s (Intel). 2. Problem DOES appear on Lenovo T14 Gen2 (AMD). 3. Problem does NOT appear on either of the above *when in the Live Installer*. I specifically checked that my dock behaved well under the Live Installer before deciding to move my workstations to Jammy. Upon logging into a fresh Jammy install, I found the following problem behavior: When the dock is plugged in, the built-in display freezes and the dock-attached displays power up but never render anything (ie, they stay black). Unplugging the USB-C cable gets mouse/keyboard response back on the built-in display. ProblemType: Bug DistroRelease: Ubuntu 22.04 Package: gnome-shell 42.0-2ubuntu1 ProcVersionSignature: Ubuntu 5.15.0-27.28-generic 5.15.30 Uname: Linux 5.15.0-27-generic x86_64 ApportVersion: 2.20.11-0ubuntu82 Architecture: amd64 CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Tue Apr 26 18:32:35 2022 DisplayManager: gdm3 InstallationDate: Installed on 2022-04-26 (0 days ago) InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Release amd64 (20220419) ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash RelatedPackageVersions: mutter-common 42.0-3ubuntu2 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/linux/+bug/1970495/+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