Public bug reported:
## Environment
- Ubuntu 26.04 LTS
- Linux 7.0.0-27-generic
- GNOME Shell (Wayland)
- AMD Ryzen 7 7840HS + Radeon 780M (Phoenix, RDNA3)
- Kernel driver: amdgpu
- linux-firmware: 20260319.git217ca6e4.1ubuntu
## Bug Description
System completely freezes (mouse and keyboard unresponsive) during normal
desktop usage. Must long-press power button to force reboot.
### Error chain from journalctl:
1. GNOME Shell assertion failures (precursor):
meta_window_set_stack_position_no_sync: assertion 'window->stack_position >=
0' failed
2. DMCUB firmware crash:
[drm] *ERROR* dc_dmub_srv_log_diagnostic_data: DMCUB error - collecting
diagnostic data (×3)
3. Display flip timeout:
[drm] *ERROR* [CRTC:364:crtc-0] flip_done timed out
4. Commit wait timeout (final freeze):
[drm] *ERROR* flip_done timed out
[drm] *ERROR* [CRTC:364:crtc-0] commit wait timed out
The DMCUB (Display MCU Binary) is the firmware running on RDNA3 GPU's
display engine microcontroller. When it crashes, the entire display
subsystem hangs, taking all input with it.
## Frequency
- Occurs every few days under normal use
- More likely when Brave browser (with GPU acceleration) is running
- No external monitor, built-in display only
- 14GB RAM, ~30-40% usage at time of crash (no OOM)
## Workaround
Only force reboot works. Temporarily disabling GPU hardware acceleration in
Brave seems to reduce frequency.
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: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Jul 17 11:40:05 2026
InstallationDate: Installed on 2026-05-02 (76 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: XIAOMI Redmi Book Pro 15 2023
ProcEnviron:
LANG=zh_CN.UTF-8
PATH=(custom, no user)
SHELL=/usr/bin/bash
TERM=xterm-ghostty
XDG_RUNTIME_DIR=<set>
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic
root=UUID=1d74dc7b-47da-4e28-b395-7e1a46e38093 ro quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/04/2023
dmi.bios.release: 1.9
dmi.bios.vendor: XIAOMI
dmi.bios.version: RMAPH5B0P0909
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: TM2209
dmi.board.vendor: XIAOMI
dmi.board.version: V24B2
dmi.chassis.asset.tag: Chassis Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: XIAOMI
dmi.ec.firmware.release: 1.9
dmi.modalias:
dmi:bvnXIAOMI:bvrRMAPH5B0P0909:bd08/04/2023:br1.9:efr1.9:svnXIAOMI:pnRedmiBookPro152023:pvr:rvnXIAOMI:rnTM2209:rvrV24B2:cvnXIAOMI:ct10:cvr:skuTM2209-46948:pfaMiLaptop:
dmi.product.family: Mi Laptop
dmi.product.name: Redmi Book Pro 15 2023
dmi.product.sku: TM2209-46948
dmi.sys.vendor: XIAOMI
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amdgpu dmcub flip-done-timeout gpu-freeze kernel phoenix radeon rdna3
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https://bugs.launchpad.net/bugs/2161041
Title:
amdgpu: Radeon 780M DMCUB error + flip_done timed out causes complete
system freeze on Ubuntu 26.04
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