Tested this on XPS 15 9560 (GTX 1050) and it does not have this problem, hotplugging works fine on it. I was using this very setup - just plugged the thunderbolt cable into a different laptop. Exact same drivers and the same linux-firmware package from upstream (1.170) that I have installed for WiFi and Bluetooth reasons.
Added the apport logs as requested. -- 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/1752165 Title: TB16 dock freezes X on hotplug when used with external displays Status in Dell Sputnik: New Status in linux package in Ubuntu: Confirmed Bug description: Precision 5520 with Quadro GPU. Latest Ubuntu 16.04, kernel Linux REDACTED 4.13.0-36-generic #40~16.04.1-Ubuntu SMP Fri Feb 16 23:25:58 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux, latest BIOS 1.7.0 released 12/15/2017. If it can be of any help, I can get this tested on an XPS 9560 (GTX 1050) too. Steps to reproduce: 1. Plug in monitors into DP and miniDP on the dock. In my case, DP-to-DVI cables are used, but I doubt that it matters. 2. Ubuntu 16.04 GNOME + nVidia drivers with PRIME. 3. Select nVidia GPU in PRIME settings, reboot if needed. 4. Either boot with the dock connected or connect it after booting into user session. 5. Set up monitors if necessary. At this point everything should be working fine. 6. Disconnect the dock, give it a moment to adjust to the new window layout etc. 7. Re-connect the dock. Within a few seconds laptop screen should freeze and external monitors should remain blank, as if not connected. 8. Disconnect the dock. Within a few seconds laptop screen should unfreeze. There is a small chance that it won't if you repeat this procedure multiple times. Errors in dmesg indicate that i915 driver is somehow involved: [ 328.966128] [drm:intel_dp_set_idle_link_train [i915]] *ERROR* Timed out waiting for DP idle patterns [ 328.967848] [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF B idle bit [ 329.048839] [drm:intel_dp_set_idle_link_train [i915]] *ERROR* Timed out waiting for DP idle patterns [ 329.050547] [drm:intel_wait_ddi_buf_idle [i915]] *ERROR* Timeout waiting for DDI BUF C idle bit The kernel logs are flooded with these between steps 7 and 8 above. This behaviour does not occur when Intel GPU is selected in PRIME settings or when nouveau is used. However, nouveau performance leaves a lot to be desired, particularly with 3D acceleration in Windows 10 VMs. I have tried nvidia_drm.modeset=1 in boot options, but it doesn't make any difference. Other reports that may be related: https://devtalk.nvidia.com/default/topic/989704/linux/plugging-a -docking-station-w-two-monitors-into-a-quadro-m1000m-laptop-crashes- hangs-the-whole-machine/ - same error messages https://www.reddit.com/r/Dell/comments/5nas3t/tb16_dock_with_5510_ubuntulinux/ddzjlu8/?st=je63h7lw&sh=40bf8189 - "Connecting and disconnecting the TB16 sometimes freeze the laptop." https://www.dell.com/community/Sputnik/TB16-Dock-Linux-Support/m-p/5109128/highlight/true#M7466 - "Hot-plugging the screen does not work." --- ApportVersion: 2.20.1-0ubuntu2.15 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: gboiko 2491 F.... pulseaudio CurrentDesktop: GNOME DistroRelease: Ubuntu 16.04 HibernationDevice: RESUME=UUID=08bba264-8658-442f-995d-6a745925ac6c InstallationDate: Installed on 2017-10-01 (149 days ago) InstallationMedia: Ubuntu-GNOME 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801) Lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 003: ID 04f3:24a1 Elan Microelectronics Corp. Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bus 001 Device 004: ID 1bcf:2b95 Sunplus Innovation Technology Inc. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: Dell Inc. Precision 5520 NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia Package: linux (not installed) ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-36-generic root=/dev/mapper/ubuntu--gnome--vg-root ro ipv6.disable=1 net.ifnames=0 biosdevname=0 nvidia_drm.modeset=1 quiet splash vt.handoff=7 ProcVersionSignature: Ubuntu 4.13.0-36.40~16.04.1-generic 4.13.13 RelatedPackageVersions: linux-restricted-modules-4.13.0-36-generic N/A linux-backports-modules-4.13.0-36-generic N/A linux-firmware 1.170 Tags: xenial Uname: Linux 4.13.0-36-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo _MarkForUpload: True dmi.bios.date: 12/15/2017 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.7.0 dmi.board.name: 0R6JFH dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.7.0:bd12/15/2017:svnDellInc.:pnPrecision5520:pvr:rvnDellInc.:rn0R6JFH:rvrA00:cvnDellInc.:ct10:cvr: dmi.product.family: Precision dmi.product.name: Precision 5520 dmi.sys.vendor: Dell Inc. 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