[radeonsi] Tearing in fullscreen when using multiple monitors and high refresh rate
As the title says, a consistent tear line appears for any fullscreen window when all the following are met:
- Multiple monitors are used, both are running at 144 Hz.
- X.org with a compositor is used (GNOME Shell).
- V-sync is ENABLED in application.
The tear line stays in approximately the same place all the time, though it does seem to vary with system load. Either disabling one monitor or switching to <= 120 Hz fixes the issue. I suspect the reason is that the driver is doing a copy rather than a page flip and it's not able to make it in time for the next frame.
The issue occurs with any Mesa and kernel version I've tested, and with both OpenGL and Vulkan.
- GPU: RX 590
- Mesa: mesa-aco-git, Mesa 20.0.0-devel (git-8a8381dd60) (LLVM 9.0.0)
- glxinfo: glxinfo.txt
- Xorg.0.log: Xorg.0.log