[Bug 2172227] Re: USB-C external monitor not detected after upgrade to Ubuntu 26.04; restored by full power reset

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2172227 Title: USB-C external monitor not detected after upgrade to Ubuntu 26.04; restored by full power reset Status in linux package in Ubuntu: New Bug description: ## System information - Laptop: HP ZBook Firefly 14 inch G11 A Mobile Workstation PC - GPU: AMD HawkPoint1 (1002:1900), using `amdgpu` - BIOS: W82 Ver. 01.09.02 (2026-08-21) - OS: Ubuntu 26.04, upgraded from Ubuntu 24.04 - Kernels tested: 7.0.0-38-generic and 7.0.0-31-generic - Session: GNOME Wayland - External monitor: Ilyama monitor connected via USB-C, with integrated USB dock ## Problem The external monitor was no longer detected via USB-C after upgrading from Ubuntu 24.04 to Ubuntu 26.04. The same configuration had worked before the upgrade. USB keyboard and mouse connected to the monitor's integrated dock continued to work. Connecting the monitor directly via HDMI also worked. ## Diagnostics while the display was not working All external DisplayPort connectors under `/sys/class/drm/` reported `disconnected`. Only the internal display (`card1-eDP-1`) reported `connected`. Further Diagnostics: - `/sys/class/typec/` was empty. - The ACPI device `USBC000:00` existed with modalias `acpi:USBC000:PNP0CA0:` and ACPI status `15`. - The modules `ucsi_acpi`, `typec_ucsi`, `typec`, and `thunderbolt` were loaded. - The `ucsi_acpi` driver was not bound to `USBC000:00`. - Attempting to bind it manually returned `No such device (os error 19)`. - Setting `driver_override` to `ucsi_acpi` and repeating the bind attempt produced the same error. - Reloading `ucsi_acpi` did not change the result. - The kernel log contained entries for the HP UCSI ACPI tables but no further UCSI-specific messages. The kernel log also contained an `amdgpu` warning: ``` REG_WAIT timeout 1us * 100 tries - dcn31_program_compbuf_size line:141 ``` ## Tests and recovery Rebooting with the older Ubuntu kernel `7.0.0-31-generic` did not restore the USB-C display. The problem was also present with `7.0.0-38-generic`. A full power reset of the laptop (disconnecting external power, pressing power button for 15 seconds), restored the USB-C display. ## Diagnostics after recovery With the external monitor working again: ``` /sys/class/drm/card1-DP-2/status: connected /sys/class/drm/card1-eDP-1/status: connected ``` However: - `/sys/class/typec/` remained empty. - `USBC000:00` remained unbound to any driver. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-38-generic 7.0.0-38.38 ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14 Uname: Linux 7.0.0-38-generic x86_64 ApportVersion: 2.34.1-0ubuntu0.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: josias 9084 F.... wireplumber /dev/snd/controlC0: josias 9084 F.... wireplumber /dev/snd/seq: josias 9064 F.... pipewire CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Mon Oct 26 13:02:18 2026 InstallationDate: Installed on 2024-10-04 (752 days ago) InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64 (20240827.1) MachineType: HP HP ZBook Firefly 14 inch G11 A Mobile Workstation PC ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-38-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro amdgpu.dcdebugmask=0x10 crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: Upgraded to resolute on 2026-10-19 (7 days ago) dmi.bios.date: 08/21/2026 dmi.bios.release: 9.2 dmi.bios.vendor: HP dmi.bios.version: W82 Ver. 01.09.02 dmi.board.name: 8C6F dmi.board.vendor: HP dmi.board.version: KBC Version 04.55.00 dmi.chassis.type: 10 dmi.chassis.vendor: HP dmi.ec.firmware.release: 4.85 dmi.modalias: dmi:bvnHP:bvrW82Ver.01.09.02:bd08/21/2026:br9.2:efr4.85:svnHP:pnHPZBookFirefly14inchG11AMobileWorkstationPC:pvrSBKPFV3:rvnHP:rn8C6F:rvrKBCVersion04.55.00:cvnHP:ct10:cvr:skuA3YW4ET#ABH:pfa103C_5336ANHPZBook: dmi.product.family: 103C_5336AN HP ZBook dmi.product.name: HP ZBook Firefly 14 inch G11 A Mobile Workstation PC dmi.product.sku: A3YW4ET#ABH dmi.product.version: SBKPFV3 dmi.sys.vendor: HP To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2172227/+subscriptions