https://bugs.kde.org/show_bug.cgi?id=526953
Bug ID: 526953
Summary: Color resolution shows "unknown" for NVIDIA external
display (DP-2) on Wayland, cannot confirm 10 bpc
output
Classification: Plasma
Product: kwin
Version First unspecified
Reported In:
Platform: Manjaro
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: colour-management
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 197020
--> https://bugs.kde.org/attachment.cgi?id=197020&action=edit
kscreen-doctor -o
""Hello, this is my first bug report. I might be making mistakes, so sorry." On
a laptop with Intel iGPU + NVIDIA RTX 4070 (PRIME setup), the external monitor
(Samsung LC49G95T, 5120x1440, connected via DP-2 on the NVIDIA GPU) reports
"Color resolution: unknown" in kscreen-doctor, while the internal eDP-1 panel
reports "Color resolution: automatic (10), range: [6; 12] bits per color".
HDR and Wide Color Gamut are shown as enabled on DP-2.
There is no way for me to verify or select the bit depth actually used on this
output. The same monitor shows 10-bit in Windows.
STEPS TO REPRODUCE
1. Use a laptop with Intel UHD (i915) + NVIDIA RTX 4070 Max-Q (nvidia open
kernel module)
2. Connect Samsung LC49G95T via DisplayPort (output DP-2, on the NVIDIA GPU)
3. Run: kscreen-doctor -o
OBSERVED RESULT
DP-2: Color resolution: unknown
eDP-1: Color resolution: automatic (10), range: [6; 12] bits per color
- /sys/module/nvidia_drm/parameters/modeset = Y
- /sys/module/nvidia_drm/parameters/fbdev = Y
- DRM debug state shows max_requested_bpc=0 / output_bpc=0 for crtc-0
- No visible banding in a gradient test, but I cannot confirm 10 bpc is in use
EXPECTED RESULT
DP-2 should report its color resolution (or at least the supported range), as
eDP-1 does, so that the user can verify/select 10 bpc output.
SOFTWARE/OS VERSIONS
KDE Plasma Version: 6.7.4
KDE Frameworks Version: 6.29.0
Qt Version: 6.11.2
NVIDIA driver: 610.57.04 (open kernel module)
Distribution: Manjaro Linux
Session: Wayland
ADDITIONAL INFORMATION
Hardware: Intel Raptor Lake-S UHD Graphics + NVIDIA AD106M (RTX 4070 Max-Q /
Mobile)
Monitor: Samsung LC49G95T (5120x1440)
ICC profile loaded: C49G9xT.icc
HDR: enabled, peak brightness overridden to 1060 nits
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