500019 2025-02-13 20:24:44 +0000 Direct scanout is prevented by black point compensation 2026-03-27 13:17:53 +0000 1 1 4 Plasma kwin platform-drm git master Other Linux RESOLVED FIXED NOR normal --- 1 xaver.hugl kwin-bugs-null bizyaev chermnykh2001 kodatarule mpalys7274 nate ngoquang2708 rropid syed.talha.khalid https://invent.kde.org/plasma/kwin/-/commit/b97e1a374aa10e528fe361fd87a5df76b5e2017d 0 oldest_to_newest 2397714 0 xaver.hugl 2025-02-13 20:24:44 +0000 The legacy KMS matrix is only 3x3, but the way we implemented black point compensation uses a 3x4 matrix, preventing direct scanout. If we apply BPC with the LUTs instead, then we could apply it just fine without preventing direct scanout too. 2400950 1 syed.talha.khalid 2025-02-21 04:36:10 +0000 Can confirm direct scannout doesn't work when Color profile ICC/Built in is selected with prefer efficiency. But setting color profile to none works as it should. 2407483 2 kodatarule 2025-03-14 07:17:28 +0000 I have noticed that even with color profile set to none the red "Compositing" sign still shows, not triggering direct scanout. This is a clean install of CachyOS, I was wondering why there was nearly 10fps deficit compared to Gnome for a long time and this seems to be the reason as to why. Operating System: CachyOS Linux KDE Plasma Version: 6.3.3 KDE Frameworks Version: 6.11.0 Qt Version: 6.8.2 Kernel Version: 6.13.6-2-cachyos (64-bit) Graphics Platform: Wayland Processors: 16 × AMD Ryzen 7 5800X3D 8-Core Processor Memory: 31,3 GiB of RAM Graphics Processor: NVIDIA GeForce RTX 3090 2407484 3 kodatarule 2025-03-14 07:26:07 +0000 In addition, I did some more tests and even on a single monitor the red "Compositing" remains, effectively not letting direct scanout work at all(color profile set to none). I am not sure if this is nvidia driver bug or something in KDE, if any logs are needed, please let me know so I can provide. 2407486 4 kodatarule 2025-03-14 07:35:01 +0000 Apologies for another reply, just wanted to say that I tested on an amd+nvidia laptop and the red "compositing" still stays on. 2419458 5 bug-janitor 2025-04-27 22:37:10 +0000 A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/7567 2420203 6 xaver.hugl 2025-04-30 15:53:15 +0000 Git commit faac87b9642c47a2afe0228216c0ef9063c138eb by Xaver Hugl. Committed on 30/04/2025 at 15:39. Pushed by zamundaaa into branch 'master'. core/colorpipeline: optimize out black point compensation M +14 -0 autotests/test_colorspaces.cpp M +28 -0 src/core/colorpipeline.cpp https://invent.kde.org/plasma/kwin/-/commit/faac87b9642c47a2afe0228216c0ef9063c138eb 2420209 7 xaver.hugl 2025-04-30 16:22:17 +0000 Git commit b97e1a374aa10e528fe361fd87a5df76b5e2017d by Xaver Hugl. Committed on 30/04/2025 at 16:04. Pushed by zamundaaa into branch 'Plasma/6.3'. core/colorpipeline: optimize out black point compensation (cherry picked from commit faac87b9642c47a2afe0228216c0ef9063c138eb) M +14 -0 autotests/test_colorspaces.cpp M +28 -0 src/core/colorpipeline.cpp https://invent.kde.org/plasma/kwin/-/commit/b97e1a374aa10e528fe361fd87a5df76b5e2017d 2420354 8 rropid 2025-05-01 06:46:59 +0000 (In reply to Zamundaaa from comment #7) > Git commit b97e1a374aa10e528fe361fd87a5df76b5e2017d by Xaver Hugl. > Committed on 30/04/2025 at 16:04. > Pushed by zamundaaa into branch 'Plasma/6.3'. > > core/colorpipeline: optimize out black point compensation > (cherry picked from commit faac87b9642c47a2afe0228216c0ef9063c138eb) > > M +14 -0 autotests/test_colorspaces.cpp > M +28 -0 src/core/colorpipeline.cpp > > https://invent.kde.org/plasma/kwin/-/commit/ > b97e1a374aa10e528fe361fd87a5df76b5e2017d Is there something else required besides using a kwin with this patch? I tried the Plasma/6.3 branch here and direct scanout doesn't seem to work with an ICC profile or the "built-in" setting. It only works with color profile set to "none". I'm using AMD graphics. Something else I happened to notice because there's a bug with regards to hardware cursor gamma right now on AMD RDNA 4: kwin seems to switch to a software cursor in fullscreen windows (maybe only with VRR enabled?). The use of a software cursor then also seems to break direct scanout. I tried experimenting with environment variables and setting KWIN_DRM_DONT_FORCE_AMD_SW_CURSOR=1 keeps the hardware cursor enabled for fullscreen. 2420589 9 xaver.hugl 2025-05-02 12:47:44 +0000 > Is there something else required besides using a kwin with this patch? I tried the Plasma/6.3 branch here and direct scanout doesn't seem to work with an ICC profile or the "built-in" setting. It only works with color profile set to "none". It depends on your settings. If you have color accuracy set to "prefer accuracy", that will prevent direct scanout in most situations. Because driver APIs are still quite lacking, having a visible cursor also often prevents it. > I tried experimenting with environment variables and setting KWIN_DRM_DONT_FORCE_AMD_SW_CURSOR=1 keeps the hardware cursor enabled for fullscreen. Right, we can probably disable that workaround by default now 2422068 10 kodatarule 2025-05-08 13:19:32 +0000 Just updated to plasma 6.3.5 on both PC desktop and laptop, both are still not triggering the direct scanout. I have also tried to make the color profile to none with no success, as well as single monitor setup which still fails to trigger the direct scanout. 2427676 11 xaver.hugl 2025-05-26 15:41:28 +0000 There can still be other things that prevent direct scanout, like active KWin effects or driver bugs