[Bug 2160608] [NEW] DisplayPort-over-Thunderbolt external monitor not detected at warm-boot

Public bug reported: Dock: Dell WD19TB, external monitor connected to it does not show up in kubuntu 26.04 after "reboot" command. Rest of devices on the dock work fine (usb keyboards etc). It works from cold start. What helps if this happens is either unplug the dock from both tb and power, and reconnect, or do the following: echo 0000:00:0d.2 | sudo tee /sys/bus/pci/drivers/thunderbolt/unbind sleep 2 echo 0000:00:0d.2 | sudo tee /sys/bus/pci/drivers/thunderbolt/bind Summary: DisplayPort-over-Thunderbolt external monitor not restored after warm reboot on Meteor Lake — TB connection manager tears down the DP tunnel before the GPU driver is ready, tunnel never recreated. Hardware: MSI Prestige 13 AI Evo A1MG (Meteor Lake-P) Host TB: Intel Meteor Lake-P Thunderbolt 4 NHI #0 [8086:7ec2], driver thunderbolt Dock: Dell WD19TB (Intel JHL7440 Titan Ridge, Thunderbolt 3), single external monitor via DP-over-TB Session: Wayland (KDE Plasma), Kubuntu 26.04 Kernel: 7.0.0-27-generic #27-Ubuntu SMP PREEMPT_DYNAMIC Thu Jun 18 2026 What happens: After a warm reboot (reboot, not cold power-off), the external monitor connected via DisplayPort-over-Thunderbolt stays dark. Cold boot works; warm reboot does not. dmesg shows the DP tunnel being torn down among the earliest kernel messages, i.e. before the i915/xe display driver is up: thunderbolt 0-3: Dell WD19TB Thunderbolt Dock thunderbolt 0-0:3.1: new retimer found, vendor=0x8087 device=0xd9c thunderbolt 0000:00:0d.2: 0:5 <-> 3:11 (DP): not active, tearing down The tunnel is destroyed and never recreated, because at teardown time the DP source (iGPU) is not yet driving it, and no later hotplug event triggers re-tunneling. Recovery (confirms HW is fine, this is a boot-ordering race): Physically unplugging/replugging the TB cable after boot → monitor comes up immediately, or Rebinding the NHI after the GPU driver is loaded works too: echo 0000:00:0d.2 > /sys/bus/pci/drivers/thunderbolt/unbind echo 0000:00:0d.2 > /sys/bus/pci/drivers/thunderbolt/bind Regression note: Probably similar teardown signature as reported on Ubuntu 26.04 for Panther Lake/xe, where 7.0.0-22 regressed and 7.0.0-15 worked. I'm on 7.0.0-27 on Meteor Lake and it still occurs — so the fix has not landed for this platform. Workaround in use: systemd oneshot unit that rebinds the NHI after graphical.target. boltctl shows the dock authorizes cleanly (iommu+user, auto-auth OK), so this is not an authorization issue. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-27-generic 7.0.0-27.27 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Tue Jul 14 12:38:15 2026 InstallationDate: Installed on 2026-07-13 (1 days ago) InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423) MachineType: Micro-Star International Co., Ltd. Prestige 13 AI Evo A1MG ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-27-generic root=UUID=523ca483-c48f-4f58-bf0b-74682d2d8535 ro quiet cryptdevice=UUID=77a13756-e087-418d-857e-9bd8d72aa6d5:luks-77a13756-e087-418d-857e-9bd8d72aa6d5 root=/dev/mapper/luks-77a13756-e087-418d-857e-9bd8d72aa6d5 splash PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/04/2025 dmi.bios.release: 1.13 dmi.bios.vendor: American Megatrends International, LLC. dmi.bios.version: E13Q2IMS.10D dmi.board.asset.tag: Default string dmi.board.name: MS-13Q2 dmi.board.vendor: Micro-Star International Co., Ltd. dmi.board.version: REV:1.0 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: Micro-Star International Co., Ltd. dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInternational,LLC.:bvrE13Q2IMS.10D:bd11/04/2025:br1.13:svnMicro-StarInternationalCo.,Ltd.:pnPrestige13AIEvoA1MG:pvrREV1.0:rvnMicro-StarInternationalCo.,Ltd.:rnMS-13Q2:rvrREV1.0:cvnMicro-StarInternationalCo.,Ltd.:ct10:cvrN/A:sku13Q2.1:pfaPrestige: dmi.product.family: Prestige dmi.product.name: Prestige 13 AI Evo A1MG dmi.product.sku: 13Q2.1 dmi.product.version: REV:1.0 dmi.sys.vendor: Micro-Star International Co., Ltd. ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug resolute wayland-session -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2160608 Title: DisplayPort-over-Thunderbolt external monitor not detected at warm- boot Status in linux package in Ubuntu: New Bug description: Dock: Dell WD19TB, external monitor connected to it does not show up in kubuntu 26.04 after "reboot" command. Rest of devices on the dock work fine (usb keyboards etc). It works from cold start. What helps if this happens is either unplug the dock from both tb and power, and reconnect, or do the following: echo 0000:00:0d.2 | sudo tee /sys/bus/pci/drivers/thunderbolt/unbind sleep 2 echo 0000:00:0d.2 | sudo tee /sys/bus/pci/drivers/thunderbolt/bind Summary: DisplayPort-over-Thunderbolt external monitor not restored after warm reboot on Meteor Lake — TB connection manager tears down the DP tunnel before the GPU driver is ready, tunnel never recreated. Hardware: MSI Prestige 13 AI Evo A1MG (Meteor Lake-P) Host TB: Intel Meteor Lake-P Thunderbolt 4 NHI #0 [8086:7ec2], driver thunderbolt Dock: Dell WD19TB (Intel JHL7440 Titan Ridge, Thunderbolt 3), single external monitor via DP-over-TB Session: Wayland (KDE Plasma), Kubuntu 26.04 Kernel: 7.0.0-27-generic #27-Ubuntu SMP PREEMPT_DYNAMIC Thu Jun 18 2026 What happens: After a warm reboot (reboot, not cold power-off), the external monitor connected via DisplayPort-over-Thunderbolt stays dark. Cold boot works; warm reboot does not. dmesg shows the DP tunnel being torn down among the earliest kernel messages, i.e. before the i915/xe display driver is up: thunderbolt 0-3: Dell WD19TB Thunderbolt Dock thunderbolt 0-0:3.1: new retimer found, vendor=0x8087 device=0xd9c thunderbolt 0000:00:0d.2: 0:5 <-> 3:11 (DP): not active, tearing down The tunnel is destroyed and never recreated, because at teardown time the DP source (iGPU) is not yet driving it, and no later hotplug event triggers re-tunneling. Recovery (confirms HW is fine, this is a boot-ordering race): Physically unplugging/replugging the TB cable after boot → monitor comes up immediately, or Rebinding the NHI after the GPU driver is loaded works too: echo 0000:00:0d.2 > /sys/bus/pci/drivers/thunderbolt/unbind echo 0000:00:0d.2 > /sys/bus/pci/drivers/thunderbolt/bind Regression note: Probably similar teardown signature as reported on Ubuntu 26.04 for Panther Lake/xe, where 7.0.0-22 regressed and 7.0.0-15 worked. I'm on 7.0.0-27 on Meteor Lake and it still occurs — so the fix has not landed for this platform. Workaround in use: systemd oneshot unit that rebinds the NHI after graphical.target. boltctl shows the dock authorizes cleanly (iommu+user, auto-auth OK), so this is not an authorization issue. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-27-generic 7.0.0-27.27 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Tue Jul 14 12:38:15 2026 InstallationDate: Installed on 2026-07-13 (1 days ago) InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423) MachineType: Micro-Star International Co., Ltd. Prestige 13 AI Evo A1MG ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-27-generic root=UUID=523ca483-c48f-4f58-bf0b-74682d2d8535 ro quiet cryptdevice=UUID=77a13756-e087-418d-857e-9bd8d72aa6d5:luks-77a13756-e087-418d-857e-9bd8d72aa6d5 root=/dev/mapper/luks-77a13756-e087-418d-857e-9bd8d72aa6d5 splash PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/04/2025 dmi.bios.release: 1.13 dmi.bios.vendor: American Megatrends International, LLC. dmi.bios.version: E13Q2IMS.10D dmi.board.asset.tag: Default string dmi.board.name: MS-13Q2 dmi.board.vendor: Micro-Star International Co., Ltd. dmi.board.version: REV:1.0 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: Micro-Star International Co., Ltd. dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInternational,LLC.:bvrE13Q2IMS.10D:bd11/04/2025:br1.13:svnMicro-StarInternationalCo.,Ltd.:pnPrestige13AIEvoA1MG:pvrREV1.0:rvnMicro-StarInternationalCo.,Ltd.:rnMS-13Q2:rvrREV1.0:cvnMicro-StarInternationalCo.,Ltd.:ct10:cvrN/A:sku13Q2.1:pfaPrestige: dmi.product.family: Prestige dmi.product.name: Prestige 13 AI Evo A1MG dmi.product.sku: 13Q2.1 dmi.product.version: REV:1.0 dmi.sys.vendor: Micro-Star International Co., Ltd. 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