** Summary changed: - Display flickering when DG1 (Iris Xe MAX) is enabled on Acer Swift SF314-510G (TigerLake iGPU + DG1 hybrid) + External monitor flickers when DG1 (Iris Xe MAX) is enabled on Acer Swift SF314-510G (TigerLake + DG1 hybrid graphics)
** Description changed: Summary: - Severe desktop flickering occurs on Kubuntu 24.04.3 LTS when both integrated TigerLake Iris Xe Graphics and discrete Iris Xe MAX (DG1) GPUs are initialized by the i915 driver. - The issue disappears immediately when the DG1 is not force-probed. + On Kubuntu 24.04.3 LTS, the external monitor flickers severely when the discrete Intel Iris Xe MAX (DG1) GPU is initialized via i915.force_probe=*. + The issue only affects external display output, while the built-in laptop screen remains stable. + Disabling DG1 (removing force_probe=*) instantly resolves the issue. System Information Distribution: Kubuntu 24.04.3 LTS (Noble Numbat) Desktop Environment: KDE Plasma 5.27.12 Kernel: 6.14.0-33-generic Host: Acer Swift SF314-510G (BIOS V1.13) CPU: Intel Core i5-1135G7 (Tiger Lake, 4C/8T) Integrated GPU: Intel Iris Xe Graphics (GT2, Device ID 0x9A49) Discrete GPU: Intel Iris Xe MAX (DG1, Device ID 0x4905) Display Server: X11 (KWin compositor) Driver: i915 Firmware versions (loaded successfully): i915/tgl_dmc_ver2_12.bin i915/dg1_dmc_ver2_02.bin i915/dg1_guc_70.bin i915/dg1_huc.bin + + Hardware Setup + + Internal display: 14" 1920×1080 built-in panel (connected to iGPU, + stable) + + External display: 24" Full HD monitor connected via HDMI → flickering + + Connection method: HDMI output from laptop + Steps to Reproduce Edit /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.force_probe=* i915.enable_psr=0" Run: sudo update-grub sudo reboot - After boot, both GPUs (iGPU 0x9A49 and DG1 0x4905) are initialized: + After boot, both GPUs are initialized: [drm] Found tigerlake/uy (device ID 9a49) [drm] Found dg1 (device ID 4905) - Desktop session starts flickering constantly: + External display starts to flicker rapidly: - Wallpaper disappears + Internal (laptop) screen is unaffected. - Right-click menu stops responding - - Plasma shell reloads repeatedly - - Removing i915.force_probe=* and rebooting fixes the issue completely. + Removing i915.force_probe=* and rebooting → flickering gone. Expected Behavior - System should remain stable with both GPUs initialized, allowing DG1 to - handle compute or rendering workloads. + Both displays (internal and external) should remain stable when DG1 is + initialized, and DG1 should be available for offload/render workloads. Actual Behavior - Severe flickering, broken compositor, and unstable desktop when DG1 is - initialized. + External monitor flickers continuously when DG1 (device 4905) is active. + Internal screen remains normal. Workaround Boot with DG1 disabled: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.enable_psr=0" - → Flickering disappears instantly, system remains smooth and stable. + → System runs smoothly with no flickering. Relevant dmesg Output i915 0000:03:00.0: [drm] Found dg1 (device ID 4905) i915 0000:03:00.0: [drm] GT0: GUC: submission enabled i915 0000:03:00.0: [drm] Cannot find any crtc or sizes Additional Notes - This system uses a hybrid configuration (TigerLake iGPU + DG1 dGPU). + This system uses a hybrid graphics configuration: + TigerLake iGPU handles the internal panel, while DG1 is a discrete PCIe GPU. - DG1 firmware loads correctly but does not attach to any display output - (Cannot find any crtc or sizes). + DG1 firmware loads properly but fails to drive any connected display (no + CRTC). - Possibly related to multi-GPU handling regression in i915 for DG1 on - hybrid laptops. + Flicker likely caused by compositor instability or framebuffer + contention between GPUs. - Kernel tainted message appears when DG1 is force-probed: + dmesg shows kernel tainted message: Force probing unsupported Device ID 4905, tainting kernel - - ProblemType: Bug - DistroRelease: Ubuntu 24.04 - Package: linux-image-6.14.0-33-generic 6.14.0-33.33~24.04.1 - ProcVersionSignature: Ubuntu 6.14.0-33.33~24.04.1-generic 6.14.11 - Uname: Linux 6.14.0-33-generic x86_64 - ApportVersion: 2.28.1-0ubuntu3.8 - Architecture: amd64 - AudioDevicesInUse: - USER PID ACCESS COMMAND - /dev/snd/controlC0: muthi 1783 F.... pipewire - muthi 1785 F.... wireplumber - /dev/snd/controlC1: muthi 1785 F.... wireplumber - /dev/snd/seq: muthi 1783 F.... pipewire - CRDA: N/A - CasperMD5CheckResult: unknown - CurrentDesktop: KDE - Date: Tue Oct 28 12:18:25 2025 - InstallationDate: Installed on 2025-10-27 (1 days ago) - InstallationMedia: Kubuntu 24.04.3 LTS "Noble Numbat" - Release amd64 (20250805.1) - MachineType: Acer Swift SF314-510G - ProcFB: 0 i915drmfb - ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.14.0-33-generic root=UUID=f44d5586-9aa3-4b44-943f-eac9451e5525 ro quiet splash i915.force_probe=9a49 i915.enable_psr=0 i915.enable_fbc=0 i915.enable_dc=0 vt.handoff=7 - RelatedPackageVersions: - linux-restricted-modules-6.14.0-33-generic N/A - linux-backports-modules-6.14.0-33-generic N/A - linux-firmware 20240318.git3b128b60-0ubuntu2.19 - SourcePackage: linux-hwe-6.14 - UpgradeStatus: No upgrade log present (probably fresh install) - dmi.bios.date: 10/28/2022 - dmi.bios.release: 1.13 - dmi.bios.vendor: Insyde Corp. - dmi.bios.version: V1.13 - dmi.board.asset.tag: Type2 - Board Asset Tag - dmi.board.name: Brahma_TL - dmi.board.vendor: TGL - dmi.board.version: V1.13 - dmi.chassis.type: 10 - dmi.chassis.vendor: Acer - dmi.chassis.version: Chassis Version - dmi.ec.firmware.release: 1.13 - dmi.modalias: dmi:bvnInsydeCorp.:bvrV1.13:bd10/28/2022:br1.13:efr1.13:svnAcer:pnSwiftSF314-510G:pvrV1.13:rvnTGL:rnBrahma_TL:rvrV1.13:cvnAcer:ct10:cvrChassisVersion:sku0000000000000000: - dmi.product.family: Swift 3X - dmi.product.name: Swift SF314-510G - dmi.product.sku: 0000000000000000 - dmi.product.version: V1.13 - dmi.sys.vendor: Acer -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2129991 Title: External monitor flickers when DG1 (Iris Xe MAX) is enabled on Acer Swift SF314-510G (TigerLake + DG1 hybrid graphics) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.14/+bug/2129991/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
