I worked on this issue all day thinking that it was tempature, cpu, gpu, cables, ports etc. And then I thought has there been a kernel change and bless pat I was correct. below is what i found....
Random screen flashes under CPU load on AMD Renoir iGPU after 7.0.0-34 → 7.0.0-38 upgrade Description Hardware: Beelink SER4 mini PC, AMD Ryzen 7 4800U (Renoir iGPU, DCN 2.1), 32 GB RAM Display: 1920x1080 @ 60 Hz over HDMI (HDMI-A-2) OS: Kubuntu 26.04, KDE Plasma (Wayland) Problem: With kernel 7.0.0-38-generic, the screen randomly flashes whenever the CPU is under sustained heavy load (HandBrake encoding, or stress-ng --cpu 0). Flashes appear within a few minutes of load starting. Booting 7.0.0-34-generic on the same system, with the same settings, gives no flashes over 25+ minutes of full CPU load (HandBrake) plus ~50% GPU load. Reproduce: stress-ng --cpu 0 --timeout 20m on 7.0.0-38. Ruled out: - HDMI cable and ports (swapped) - Temperature (CPU Tctl ~75°C at full load) - Power draw (still flashes with CPU capped to 1.4 GHz, PPT ~10 W) - CPU scheduling (still flashes with stress-ng at nice 19) - Clocksource (TSC was falling back to HPET; tsc=reliable did not change it) - GPU clock switching (power_dpm_force_performance_level=high did not change it) - amdgpu.sg_display=0 is set on both kernels No amdgpu/drm errors appear in dmesg when the flashes occur. This looks like a regression between 7.0.0-34 and 7.0.0-38. Reverted back to 7.0.0-34 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2169181 Title: Visual background flickering and pixel artifacts after updating to kernel 7.0.0-38 (regression from 7.0.0-34) | Ubuntu 26.04 | AMD Radeon RX 9060 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2169181/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
