*** This bug is a duplicate of bug 2163303 ***
https://bugs.launchpad.net/bugs/2163303
Public bug reported:
After upgrading `linux-firmware` from version
`20240318.git3b128b60-0ubuntu2.27` to
`20240318.git3b128b60-0ubuntu2.29`, the desktop on my discrete AMD
Radeon RX 6900 XT (Navi 21) fails to render correctly. The screen
appears split/corrupted (framebuffer allocated at double width, e.g.
3840x1080 instead of 1920x1080), while the integrated AMD GPU (Ryzen
Raphael APU) on the same system continues to work perfectly fine.
Downgrading `linux-firmware` to version
`20240318.git3b128b60-0ubuntu2.26` immediately and completely resolves
the issue.
## System information
- OS: Zorin OS (Ubuntu 24.04 base)
- Kernel tested: both 6.17.0-35-generic and 7.0.0-28-generic — issue present on
both (rules out kernel regression)
- Xorg and Wayland sessions both tested — issue present on both (rules out
display server regression)
- Discrete GPU: AMD Radeon RX 6900 XT (Navi 21) — `lspci`: `03:00.0 VGA
compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 21 [Radeon
RX 6800/6800 XT / 6900 XT] (rev c1)`, kernel driver `amdgpu`
- Integrated GPU: AMD Radeon Graphics (Raphael) — `0e:00.0`, kernel driver
`amdgpu` — works correctly in all tests
- Single monitor, connected via direct DisplayPort cable (no dock/hub/MST),
running 1080p at 144Hz+
- Tested and confirmed working correctly with the exact same
hardware/cable/monitor on a live USB (unrelated OS image), ruling out hardware
failure
## Steps to reproduce
1. Have a system with a Navi 21 GPU (RX 6800/6800 XT/6900 XT) as
primary/discrete GPU alongside an integrated AMD GPU.
2. Update `linux-firmware` to `20240318.git3b128b60-0ubuntu2.29` (came in via
standard apt upgrade on 2026-08-14).
3. Reboot with the discrete GPU active/connected to the display.
4. Observe the desktop rendering split or corrupted (screen appears as if
divided into two halves).
## Expected behavior
Desktop renders normally on the discrete GPU, as it did prior to the
`linux-firmware` update.
## Actual behavior
Desktop is split/corrupted. Relevant kernel/Xorg log excerpts from the
affected boot:
```
kernel: amdgpu 0000:03:00.0: [drm] Loading DMUB firmware via PSP:
version=0x01000000
kernel: amdgpu 0000:03:00.0: smu driver if version = 0x00000040, smu fw if
version = 0x00000041, smu fw program = 0, version = 0x003a5900 (58.89.0)
kernel: amdgpu 0000:03:00.0: SMU is initialized successfully!
kernel: amdgpu 0000:03:00.0: [drm] Wait for DMUB auto-load failed: 3
kernel: amdgpu 0000:03:00.0: [drm] DMUB hardware initialized: version=0x01000000
...
kernel: amdgpu 0000:03:00.0: [drm] REG_WAIT timeout 1us * 100000 tries -
mpc2_assert_idle_mpcc line:481
(EE) AMDGPU(G0): drmmode_do_crtc_dpms cannot get last vblank counter
kernel: amdgpu 0000:03:00.0: [drm] enabling link 2 failed: 15
kernel: amdgpu 0000:03:00.0: SMU: No response msg_reg: 29 resp_reg: 0
kernel: amdgpu 0000:03:00.0: Failed to disable gfxoff!
(II) AMDGPU(0): Allocate new frame buffer 3840x1080
```
Note the framebuffer is allocated at double the monitor's actual
horizontal resolution (3840 instead of 1920), which visually manifests
as the split-screen symptom.
By contrast, the integrated GPU on the same boot initializes cleanly with no
errors:
```
kernel: amdgpu 0000:0e:00.0: [drm] Loading DMUB firmware via PSP:
version=0x05001C00
kernel: amdgpu 0000:0e:00.0: SMU is initialized successfully!
kernel: amdgpu 0000:0e:00.0: [drm] DMUB hardware initialized: version=0x05001C00
```//no failure between "Loading DMUB" and "hardware initialized" for the iGPU,
unlike the dGPU.
## Diagnostic steps taken (to rule out other causes)
- Tested with both kernel 6.17.0-35-generic and 7.0.0-28-generic — same failure
on both, ruling out a kernel-only regression.
- Tested with both Xorg and Wayland sessions — same failure on both.
- Tested a different DisplayPort cable and monitor port — same failure, ruling
out cable/connector fault.
- Checked monitor OSD for any MST/PBP/Tiled Display setting — none present on
this monitor.
- Booted a live USB (independent OS/kernel/firmware) with the same
hardware/cable/monitor — desktop rendered correctly, ruling out a hardware
fault on the GPU or monitor.
- Downgraded only `linux-firmware` (keeping the installed kernel unchanged)
from `.29` to `.26` — issue resolved immediately, confirming this
package/version is the cause.
## Workaround
Downgrade `linux-firmware` to `20240318.git3b128b60-0ubuntu2.26` and
hold the package:
```bash
cd /tmp
wget
https://archive.ubuntu.com/ubuntu/pool/main/l/linux-firmware/linux-firmware_20240318.git3b128b60-0ubuntu2.26_amd64.deb
sudo apt install ./linux-firmware_20240318.git3b128b60-0ubuntu2.26_amd64.deb
sudo apt-mark hold linux-firmware
sudo update-initramfs -u
sudo reboot
```
## Additional notes
Versions `.27` and `.28` were no longer available in the archive pool to
bisect further, so I could not narrow down exactly which point release
between `.26` and `.29` introduced the regression — only that `.26`
works and `.29` does not. If a maintainer can point me to a way to test
`.27`/`.28` (e.g. via a PPA or snapshot archive), I'm happy to help
bisect further.
** Affects: linux-firmware (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2164414
Title:
.29 breaks display output on AMD RX 6900 XT (Navi 21) -
split/corrupted screen, DMUB auto-load failure
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