Upgrading to kde-plasma/kwin-6.5.0-r1 on Gento (aka 6.5.0 + patches from KDE up to commit ac533b2cea19402e7b2580d8e1d99b5ee59e7357) the graphical environment doesn't start showing black screen. Downgrading to kde-plasma/kwin-6.5.0 (aka 6.5.0 official Tag) the system works again. I suppose the issue is from the backported patches (but I cannot bisect this time). Instead, X11 session works Reproducible: Always Steps to Reproduce: 1. Upgrade to kde-plasma/kwin-6.5.0-r1 2. Restart the system 3. Login using KWIN Wayland Actual Results: The system shows black screen Expected Results: KDE up and running kwin_wayland shows a lot of "kwin_wayland_drm: Atomic test failed! Invalid argument" Installed x11-drivers/nvidia-drivers-680.95.05 lspci: 01:00.0 3D controller: NVIDIA Corporation GP107M [GeForce GTX 1050 3 GB Max-Q] (rev a1) Kernel: sys-kernel/gentoo-kernel-bin-6.17.5
Created attachment 186230 [details] kwin_wayland logs from journalctl
Please follow https://invent.kde.org/plasma/kwin/-/wikis/Debugging/Debugging-DRM-issues to get a drm debug log of why it doesn't work. Alternative, a bisect would be very useful.
The offending commit seems to be this: "backends/drm: expand the implicit modifier fallback to low bandwidth formats" https://invent.kde.org/plasma/kwin/-/commit/f67e5b6f2b7a7d23fbb343c235c2f4a4c0b6f0ba ciao luigi
Additional information about my environment: <pre> Portage 3.0.69 (python 3.13.9-final-0, default/linux/amd64/23.0/desktop/plasma/systemd, gcc-15, glibc-2.42-r1, 6.17.5-gentoo-dist x86_64) ================================================================= System uname: Linux-6.17.5-gentoo-dist-x86_64-Intel-R-_Core-TM-_i7-9750H_CPU_@_2.60GHz-with-glibc2.42 KiB Mem: 32591224 total, 11097236 free KiB Swap: 67108860 total, 67105844 free Head commit of repository comio-overlay: 3b331507ef97701ddd68020632e01c79f54888ab Timestamp of repository guru: Tue, 28 Oct 2025 06:03:33 +0000 Head commit of repository guru: a78c9957a26b89d7612c062600d341463877972e Head commit of repository mv: 044c9f9c5cebbfded20c34bbee55d3d5a2ca20be Head commit of repository plex-overlay: 421527710bad6c2c0f24bf683fd29c60039d2b5d Head commit of repository wayland-desktop: 2102eb44b4e9571112fc2edb642129abd075b840 Timestamp of repository gentoo: Tue, 28 Oct 2025 07:34:33 +0000 Head commit of repository gentoo: 8e08bef2fc3b427881d00776b9661ab349815a7c sh bash 5.3_p3-r3 ld GNU ld (Gentoo 2.45 p3) 2.45.0 app-misc/pax-utils: 1.3.8::gentoo app-shells/bash: 5.3_p3-r3::gentoo dev-build/autoconf: 2.72-r4::gentoo dev-build/automake: 1.18.1::gentoo dev-build/cmake: 4.1.2-r1::gentoo dev-build/libtool: 2.5.4::gentoo dev-build/make: 4.4.1-r101::gentoo dev-build/meson: 1.9.1::gentoo dev-lang/perl: 5.42.0::gentoo dev-lang/python: 3.13.9::gentoo, 3.14.0::gentoo dev-lang/rust-bin: 1.90.0::gentoo llvm-core/clang: 20.1.8::gentoo, 21.1.4::gentoo llvm-core/lld: 20.1.8::gentoo llvm-core/llvm: 20.1.8::gentoo, 21.1.4::gentoo sys-apps/baselayout: 2.18::gentoo sys-apps/sandbox: 2.46::gentoo sys-apps/systemd: 258.1::gentoo sys-devel/binutils: 2.45-r1::gentoo sys-devel/binutils-config: 5.6::gentoo sys-devel/gcc: 15.2.1_p20251018::gentoo sys-devel/gcc-config: 2.12.2::gentoo sys-kernel/linux-headers: 6.17-r1::gentoo (virtual/os-headers) sys-libs/glibc: 2.42-r1::gentoo media-libs/mesa: 25.2.5::gentoo x11-drivers/nvidia-drivers: 580.95.05::gentoo sys-kernel/gentoo-kernel-bin: 6.17.5::gentoo </pre>
That's quite surprising. Could you still get a drm debug log? I can't think of a reason for why the commit would cause the failure, rather than help with it, and neither I nor a colleague could reproduce the issue with an NVidia GPU to debug locally.
Created attachment 186277 [details] dmesg + drm debug
kwin-6.5.1 is also affected by issue. Reverting "backends/drm: prevent accessing the pipeline when it's already removed" https://invent.kde.org/plasma/kwin/-/commit/f5415995c51d6b0e68087a386e16c2003ba5c314 (required to cleaning reverting the following) and "backends/drm: expand the implicit modifier fallback to low bandwidth formats" https://invent.kde.org/plasma/kwin/-/commit/ade8159b2730a89d698d49db87032fa65fc62c27 fix issue on my system. ciao luigi
lspci: 00:00.0 Host bridge: Intel Corporation 8th/9th Gen Core Processor Host Bridge / DRAM Registers (rev 07) 00:01.0 PCI bridge: Intel Corporation 6th-10th Gen Core Processor PCIe Controller (x16) (rev 07) 00:02.0 VGA compatible controller: Intel Corporation CoffeeLake-H GT2 [UHD Graphics 630] 00:04.0 Signal processing controller: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 07) 00:08.0 System peripheral: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model 00:12.0 Signal processing controller: Intel Corporation Cannon Lake PCH Thermal Controller (rev 10) 00:13.0 Serial controller: Intel Corporation Device a37c (rev 10) 00:14.0 USB controller: Intel Corporation Cannon Lake PCH USB 3.1 xHCI Host Controller (rev 10) 00:14.2 RAM memory: Intel Corporation Cannon Lake PCH Shared SRAM (rev 10) 00:14.3 Network controller: Intel Corporation Cannon Lake PCH CNVi WiFi (rev 10) 00:15.0 Serial bus controller: Intel Corporation Cannon Lake PCH Serial IO I2C Controller #0 (rev 10) 00:15.1 Serial bus controller: Intel Corporation Cannon Lake PCH Serial IO I2C Controller #1 (rev 10) 00:16.0 Communication controller: Intel Corporation Cannon Lake PCH HECI Controller (rev 10) 00:17.0 SATA controller: Intel Corporation Cannon Lake Mobile PCH SATA AHCI Controller (rev 10) 00:1b.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #17 (rev f0) 00:1d.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #9 (rev f0) 00:1f.0 ISA bridge: Intel Corporation HM370 Chipset LPC/eSPI Controller (rev 10) 00:1f.3 Multimedia audio controller: Intel Corporation Cannon Lake PCH cAVS (rev 10) 00:1f.4 SMBus: Intel Corporation Cannon Lake PCH SMBus Controller (rev 10) 00:1f.5 Serial bus controller: Intel Corporation Cannon Lake PCH SPI Controller (rev 10) 01:00.0 3D controller: NVIDIA Corporation GP107M [GeForce GTX 1050 3 GB Max-Q] (rev a1) 02:00.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02) 03:00.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02) 03:01.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02) 03:02.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02) 04:00.0 System peripheral: Intel Corporation JHL6340 Thunderbolt 3 NHI (C step) [Alpine Ridge 2C 2016] (rev 02) 3a:00.0 USB controller: Intel Corporation JHL6340 Thunderbolt 3 USB 3.1 Controller (C step) [Alpine Ridge 2C 2016] (rev 02) 3b:00.0 Non-Volatile memory controller: KIOXIA Corporation NVMe SSD Controller BG4 (DRAM-less)
Oh, so the screen in question is connected to the Intel GPU, not NVidia. > [ 149.829931] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] [CRTC:80:pipe B] dbuf slices 0x1 -> 0x1, ddb (223 - 446) -> (223 - 669), active pipes 0x7 -> 0x7 > [ 149.829987] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] [CRTC:104:pipe C] dbuf slices 0x1 -> 0x1, ddb (446 - 892) -> (669 - 892), active pipes 0x7 -> 0x7 > [ 149.830043] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] Requested display configuration exceeds system DDB limitations > [ 149.830096] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] minimum required 242/199 That looks like the commit broke the implicit modifier fallback, instead of just expanding it. If you set https://invent.kde.org/plasma/kwin/-/wikis/Environment-Variables#kwin_drm_use_modifiers to 0, does that help?
Created attachment 186299 [details] Patch that could help If the env var does help, please also test the patch
(In reply to Zamundaaa from comment #9) > Oh, so the screen in question is connected to the Intel GPU, not NVidia. > > > [ 149.829931] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] [CRTC:80:pipe B] dbuf slices 0x1 -> 0x1, ddb (223 - 446) -> (223 - 669), active pipes 0x7 -> 0x7 > > [ 149.829987] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] [CRTC:104:pipe C] dbuf slices 0x1 -> 0x1, ddb (446 - 892) -> (669 - 892), active pipes 0x7 -> 0x7 > > [ 149.830043] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] Requested display configuration exceeds system DDB limitations > > [ 149.830096] i915 0000:00:02.0: [drm:skl_fixup_initial_plane_config [i915]] minimum required 242/199 > > That looks like the commit broke the implicit modifier fallback, instead of > just expanding it. If you set > https://invent.kde.org/plasma/kwin/-/wikis/Environment- > Variables#kwin_drm_use_modifiers to 0, does that help? this workaround works. thanks.
(In reply to Zamundaaa from comment #10) > Created attachment 186299 [details] > Patch that could help > > If the env var does help, please also test the patch Also the patch is ok (without the env var, of course).
Great
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8328
Git commit a33cc222f53a7c8a9b5716ab48f236f5dfc7e5b0 by Xaver Hugl. Committed on 30/10/2025 at 13:26. Pushed by zamundaaa into branch 'master'. backends/drm: fix implicit modifier fallback The per-plane format list only contains explicit modifiers, so this basically forced explicit modifiers in all cases. M +3 -7 src/backends/drm/drm_plane.cpp https://invent.kde.org/plasma/kwin/-/commit/a33cc222f53a7c8a9b5716ab48f236f5dfc7e5b0
Git commit f67a6cb896835b594cbffc8dc4f3a7a396654ade by Xaver Hugl. Committed on 30/10/2025 at 13:48. Pushed by zamundaaa into branch 'Plasma/6.5'. backends/drm: fix implicit modifier fallback The per-plane format list only contains explicit modifiers, so this basically forced explicit modifiers in all cases. (cherry picked from commit a33cc222f53a7c8a9b5716ab48f236f5dfc7e5b0) Co-authored-by: Xaver Hugl <xaver.hugl@kde.org> M +3 -7 src/backends/drm/drm_plane.cpp https://invent.kde.org/plasma/kwin/-/commit/f67a6cb896835b594cbffc8dc4f3a7a396654ade