Public bug reported:
After upgrading to linux-image-7.0.0-38-generic, a DisplayPort monitor shows ~1
ms
visual flashes (tearing-like) at 120 Hz and 144 Hz. 7.0.0-34-generic is clean
at the
same refresh rate with identical userspace.
Hardware
- GPU: AMD Radeon RX 9060 XT (gfx1200), PCI 1002:7590, driver amdgpu
- Display: HWV ZQE-CAA, 3440x1440, 165 Hz native, DP-1, 10 bpc, no DSC
- Session: GNOME Wayland (mutter 50.1), Mesa 26.0.8
Symptom
- Brief flashes on pointer motion and small damage repaints (typing in a
terminal,
overview hover, mouse movement). GL apps make it more frequent; it still
happens
with all GPU apps closed.
- Clean at 60 Hz and 100 Hz. Glitches at 120 Hz and 144 Hz.
- Clean on the GDM greeter.
Regression
- 7.0.0-34-generic: clean at 144 Hz. 7.0.0-38-generic: glitches at 144 Hz.
- Same mutter, Mesa and monitor on both; only the kernel changed.
- A second machine (AMD iGPU, internal panel, 7.0.0-34) is unaffected; it has
not
run -38 yet.
Ruled out (still glitches on -38)
- Userspace mismatch after upgrade (rebooted after full-upgrade)
- GNOME animations disabled
- Hardware cursor plane disabled (MUTTER_DEBUG_DISABLE_HW_CURSORS=1,
MUTTER_DEBUG_INHIBIT_HW_CURSOR=1, verified in gnome-shell environ)
- Overlay planes (MUTTER_DEBUG_FORCE_KMS_MODE=simple, verified)
- Link side: dp1 link_settings (4 lanes, 0x1e = HBR3), DSC state (off), max
bpc (10),
amdgpu_dm_capabilities and amdgpu_dm_dtn_log are identical between -34 and
-38 at
144 Hz. No DP link-training/DSC errors in dmesg on either kernel.
Suspect commits (from the linux 7.0.0-38.38 changelog, not bisected)
1. drm/amd/display: consolidate DCN vblank/flip handling onto ...
2. drm/amd/display: Fix DTB DTO updates breaking live pixel rate sources
3. drm/amd/display: Fix mem_type change detection for async flips
4. drm/amd/display: Handle struct drm_plane_state.ignore_damage_clips
Attached: dp1-link, dm-capabilities and dtn for both kernels, modes-DP1.txt,
monitor-edid-34.txt in all in file
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: xorg (not installed)
ProcVersionSignature: Ubuntu 7.0.0-34.34-generic 7.0.14
Uname: Linux 7.0.0-34-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct 2 18:38:04 2026
InstallationDate: Installed on 2025-02-22 (587 days ago)
InstallationMedia: Ubuntu 24.04.2 LTS "Noble Numbat" - Release amd64 (20250215)
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/zsh
TERM=tmux-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to resolute on 2026-10-02 (0 days ago)
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
** Attachment added: "evidence-combined.txt"
https://bugs.launchpad.net/bugs/2169319/+attachment/6005003/+files/evidence-combined.txt
** Package changed: xorg (Ubuntu) => linux (Ubuntu)
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https://bugs.launchpad.net/bugs/2169319
Title:
amdgpu: screen flashes at 120/144 Hz on RX 9060 XT (gfx1200),
regression 7.0.0-34 -> 7.0.0-38
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