rendering using the Intel GPU the frame rate maxes out at 60, but rendering using a AMD GPU does not appear to be bound by the display rate at all. With simple games and game menus, the frame rate can easely exceed 100 fps on a AMD 6630M, and not all apps/games has fps limiting functionality. I took a quick look at the source, and it appears to me that there is no code to synchronize to vsync when copying between prime buffers on different devices. Looking at the ati driver, it appears to force vsync synchronization when copying prime buffers when the the application is running full screen. Any chance we can get vsync synchronization for prime setups? Driver version: 2.21.15 Xorg core version: 1.14.3 P.S: Thank you to everyone who's hard work made this bug report possible =)
In progress. Maarten Lankhorst has a synchronisation mechanism for the kernel that is partially upstream which is required to sync between the two devices - and has demonstrated it with vsynced rendering between i915/nouveau so far.
Should be working now with v4.9 kernel and xorg-1.19 using DRI3 between intel/nouveau/radeon/amdgpu.
It has been kinda working for a few yeas now, but with Linux 4.9 and the latest Xorg it actually works! Thank you everyone
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