https://bugs.kde.org/show_bug.cgi?id=528017
Bug ID: 528017
Summary: HDR on AMD: "sRGB color intensity" slider has no
visible effect and wide-gamut (P3) content is clipped
to sRGB
Classification: Plasma
Product: kwin
Version First unspecified
Reported In:
Platform: EndeavourOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: colour-management
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 197808
--> https://bugs.kde.org/attachment.cgi?id=197808&action=edit
OLED MSI Monitor MAG321UX EDID
STEPS TO REPRODUCE
1. Enable HDR + Wide Color Gamut on an HDR display connected to an AMD GPU (HDR
color profile source: EDID).
2. Show saturated SDR content (solid #FF0000 / #00FF00 image) and move "sRGB
color intensity" between 0% and 100%.
3. In a color-managed browser (Chromium-based, reports `(color-gamut: p3)` =
true), show #FF0000 next to color(display-p3 1 0 0), and #00FF00 next to
color(display-p3 0 1 0).
OBSERVED RESULT
- Moving the slider from 0% to 100% makes no visible difference.
- The P3 colors look identical to the sRGB ones; nothing beyond sRGB appears to
reach the panel.
EXPECTED RESULT
- At 100%, SDR colors should become visibly more saturated (stretched to the
panel's native gamut).
- P3 red and green should look more saturated than sRGB red and green.
ADDITIONAL INFORMATION
- Reproduced on two AMD setups with different displays and connections:
- RX 7900 XTX (Navi 31, DCN 3.2) + MSI MAG 321UX OLED (QD-OLED) over
DisplayPort (HBR3 x4, DSC, 3840x2160@240, 10 bpc)
- RX 9070 XT + LG G5 OLED TV over HDMI
- On an NVIDIA GPU with mini-LED HDR monitors, the same slider visibly worked.
- The monitor has no gamut/sRGB option while in HDR mode (only "True Black 400"
/ "Peak 1000"; True Black 400 is in use).
- The panel's native gamut is wide: the login screen (SDDM on X11, SDR, no
color management) appears clearly oversaturated.
DRM state for the connector (/sys/kernel/debug/dri/1/state) shows KWin requests
BT.2020 signalling and composites in shaders:
connector[393]: DP-1
max_requested_bpc=10
colorspace=BT2020_RGB
plane[206]: plane-3 (only plane on crtc-0)
format=AB48 little-endian
color-pipeline=0
wayland-info, wp_color_manager_v1 output description for this screen (EDID
primaries are parsed correctly):
primaries_named: bt2020
tf_named: gamma22
luminances (cd/m²): min 0.0000 max 400 reference 220
target primaries (xy):
red: 0.683594 0.304688 green: 0.244141 0.708984
blue: 0.143555 0.055664 white: 0.312700 0.329000
target_luminances (cd/m²): min 0.0050 max 400
max_cll (cd/m²): 400
max_fall (cd/m²): 254
kscreen-doctor for DP-1: HDR enabled, WCG enabled, SDR brightness 220 nits, SDR
gamut wideness 50%, peak brightness override 400 nits (from HDR calibration),
max average 254 nits, HDR color profile source EDID, color power preference
"prefer accuracy", 10 bpc, VRR automatic.
Already ruled out:
- Not the 6.7 regression in bug 521759 (wrong default colorimetry / sRGB
fallback): target primaries above are the EDID values.
- Not drm/amd #5396: DCN 3.5+ only, and closed.
- Setting KWIN_DRM_USE_COLOR_PIPELINE=0 in the session environment made no
difference.
EDID of the MSI MAG 321UX attached.
SOFTWARE/OS VERSIONS
Linux: Arch Linux (EndeavourOS), kernel 7.2.11-arch1-1
KDE Plasma Version: 6.8.2
KDE Frameworks Version: 6.31.0
Qt Version: 6.12.0
Mesa: 26.2.6
linux-firmware: 20260916
Graphics Platform: Wayland
GPU: AMD Radeon RX 7900 XTX (amdgpu)
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