Public bug reported:
Hardware:
* HP ZBook Ultra G1a 14-inch Mobile Workstation
* AMD Ryzen AI Max+ PRO 395 with Radeon 8060S (Strix Halo)
* HP Thunderbolt 4 Ultra 280W G6 Dock
* Two external 3840x2160 displays at 60 Hz through the dock
* Internal notebook display enabled
Software:
* Ubuntu 24.04 LTS OEM installation
* Kernel: 6.17.0-1032-oem
* Session: Wayland
* Mesa: 25.2.8-0ubuntu0.24.04.2
* oem-stella-chippo-meta: 24.04ubuntu4
* BIOS: X89 01.05.07
* Dock firmware: 01.04.42.00, reported as the latest available version by fwupd
Problem:
During video conferences, the external display setup repeatedly blanks and
reconnects. The issue can occur several times within a few minutes. The kernel
reports an MST payload allocation timeout followed by a large number of
DisplayPort HPD interrupts.
Relevant kernel messages:
thunderbolt 0000:c5:00.5: 0: failed to allocate DP resource for port 6
amdgpu 0000:c3:00.0: [drm] *ERROR* Failed to get ACT after 3000 ms, last
status: 04
amdgpu 0000:c3:00.0: amdgpu: [drm] DMUB HPD RX IRQ callback: link_index=6
[drm] MST_DSC Send DSC disable to synaptics
[drm] MST_DSC Send DSC enable to synaptics
During one occurrence, HPD interrupts continued repeatedly for several
seconds and the ACT timeout occurred twice.
There are no accompanying GPU ring timeouts, GPU resets, or VM faults.
This appears to be a failure while updating the DisplayPort MST payload
allocation between amdgpu and the Synaptics MST/DSC controller in the
dock.
Additional observation:
When testing a monitor through the dock's HDMI output, only 3840x2160 at 30 Hz
was offered instead of 60 Hz.
Steps to reproduce:
1. Boot Ubuntu with the HP Thunderbolt 4 Ultra 280W G6 Dock connected.
2. Enable the internal display and two external 4K displays at 60 Hz.
3. Join a video conference.
4. Continue the conference for several minutes.
5. Observe the external displays blanking and reconnecting.
6. Check the kernel log for repeated DMUB HPD RX IRQ messages and “Failed to
get ACT after 3000 ms”.
Expected result:
All displays remain continuously connected and stable at their configured
resolutions and refresh rates.
Actual result:
The external display link is repeatedly renegotiated, causing visible monitor
blanking and reconnection.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-1032-oem 6.17.0-1032.32
ProcVersionSignature: Ubuntu 6.17.0-1032.32-oem 6.17.13
Uname: Linux 6.17.0-1032-oem x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue Sep 8 00:15:16 2026
InstallationDate: Installed on 2026-01-20 (230 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
MachineType: HP HP ZBook Ultra G1a 14 inch Mobile Workstation PC
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-1032-oem
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash
RelatedPackageVersions:
linux-restricted-modules-6.17.0-1032-oem N/A
linux-backports-modules-6.17.0-1032-oem N/A
linux-firmware 20240318.git3b128b60.0ubuntu3.1
SourcePackage: linux-oem-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/05/2026
dmi.bios.release: 5.7
dmi.bios.vendor: HP
dmi.bios.version: X89 Ver. 01.05.07
dmi.board.name: 8D01
dmi.board.vendor: HP
dmi.board.version: KBC Version 35.34.00
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.ec.firmware.release: 53.52
dmi.modalias:
dmi:bvnHP:bvrX89Ver.01.05.07:bd05/05/2026:br5.7:efr53.52:svnHP:pnHPZBookUltraG1a14inchMobileWorkstationPC:pvrSBKPFV3:rvnHP:rn8D01:rvrKBCVersion35.34.00:cvnHP:ct10:cvr:skuB72TBET#ABD:
dmi.product.family: 103C_5336AN HP ZBook
dmi.product.name: HP ZBook Ultra G1a 14 inch Mobile Workstation PC
dmi.product.sku: B72TBET#ABD
dmi.product.version: SBKPFV3
dmi.sys.vendor: HP
** Affects: linux-oem-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2166721
Title:
HP ZBook Ultra G1a: MST ACT timeout and HPD storm with HP G6 dock and
dual 4K60
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux-oem-6.17/+bug/2166721/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
