https://bugs.kde.org/show_bug.cgi?id=524067
Bug ID: 524067
Summary: HDR regression in KWin 6.6.6 on AMD/RADV: Cyberpunk
2077 HDR perfect on 6.6.4, washed out on 6.6.6
Classification: Plasma
Product: kwin
Version First 6.6.6
Reported In:
Platform: Kubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: colour-management
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
## DESCRIPTION
There is a reproducible HDR regression in KWin between 6.6.4 and 6.6.6 on an
AMD Radeon RX 7900 XTX using Wayland.
Cyberpunk 2077 v2.31 produces correct/perfect HDR with KWin 6.6.4, but the HDR
image becomes severely washed out/smeared with KWin 6.6.6.
The regression is reproducible by changing only the KWin packages:
* KWin 6.6.4 → HDR works correctly
* KWin 6.6.6 → HDR is incorrect
* Downgrading back to KWin 6.6.4 immediately restores correct HDR
Mesa/RADV, GPU, display, game, Wine and the game configuration were unchanged
between the two tests.
## STEPS TO REPRODUCE
1. Use KDE Plasma Wayland with an AMD Radeon RX 7900 XTX and HDR-capable
display.
2. Run Cyberpunk 2077 v2.31 through Wine/Proton with HDR enabled.
3. With KWin 6.6.4 installed, enable HDR in Cyberpunk and observe the image.
4. Upgrade KWin/Plasma to 6.6.6 and launch the same game with the same
configuration.
5. Compare the HDR image.
6. Downgrade `kwin-wayland`, `kwin-common` and `kwin-data` back to 6.6.4 and
repeat the test.
## OBSERVED RESULT
With KWin 6.6.6, HDR is severely washed out/smeared and the image is visibly
incorrect.
With KWin 6.6.4, using the same hardware, software stack and game
configuration, HDR is correct.
The regression is therefore reproducible specifically across the KWin 6.6.4 →
6.6.6 version change.
Additional tests performed on KWin 6.6.6:
* `KWIN_DISABLE_TONEMAPPING=1` — no change.
* `KWIN_DRM_NO_DIRECT_SCANOUT=1` — no change.
* `ENABLE_HDR_WSI=1` — no change.
* KWin Color Accuracy set to "Prefer Efficiency" — slightly worse.
* Removing the KORTHOS/Reflex latency layer — no improvement.
* Removing the NVIDIA/NVAPI spoofing changes Cyberpunk feature detection (FSR4
disappears), but HDR remains incorrect, so this does not explain the
regression.
## EXPECTED RESULT
Cyberpunk 2077 HDR should be rendered correctly under KWin 6.6.6, as it is
under KWin 6.6.4.
## SOFTWARE/OS VERSIONS
Operating System: Kubuntu 26.04 LTS (Ubuntu 26.04 Resolute)
KDE Plasma Version: 6.6.6 when affected; 6.6.4 when working
KDE Frameworks Version: [fill in]
Qt Version: [fill in]
KWin affected package:
`4:6.6.6-0ubuntu0.1`
Working KWin packages:
`4:6.6.4-0ubuntu1`
GPU:
AMD Radeon RX 7900 XTX
Vulkan:
RADV, Vulkan API 1.4.335
Mesa:
26.0.5 (Kisak-Mesa PPA)
Wine:
Wine 11.0
Game:
Cyberpunk 2077 v2.31
Display session:
KDE Plasma Wayland
HDR:
Enabled
## ADDITIONAL INFORMATION
The most important diagnostic result is the direct A/B test:
KWin 6.6.6: HDR broken
KWin 6.6.4: HDR perfect
I performed the downgrade using only these KWin packages:
`kwin-wayland`
`kwin-common`
`kwin-data`
APT reported that exactly these three packages would be downgraded, with no
packages removed or newly installed.
The Mesa/RADV stack remained at Mesa 26.0.5 during both tests.
This appears to be a KWin regression affecting the Wayland HDR/color-management
path used by Wine/Proton applications on AMD/RADV.
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