NVIDIA Developer Still Working On PRIME Synchronization
NVIDIA continues to be working on PRIME synchronization support to fix tearing when using this multi-GPU method. There will be support for this functionality within the proprietary NVIDIA Linux driver.
One month ago I wrote how Alex Goins of NVIDIA's Linux driver team was working to fix PRIME tearing / provider proper synchronization support. The latest patches for this were published this week so PRIME will support double-buffering.
Alex Goins wrote at the start of the newest patch series, "These patches change the xserver to support setting up PRIME with double buffering, and implement double buffered PRIME sink support in the modesetting driver. In addition to these changes, I've been working to upstream a couple of patches to the i915 DRM driver that mesh with these, and have implemented double buffered PRIME source support in the NVIDIA proprietary driver (pending release.)"
PRIME synchronization with double buffering can be toggled via a XRandR output property.
Hopefully these patches will be merged soon for X.Org Server 1.19 and that it will make it out on time around the middle of 2016. Once that happens, NVIDIA's proprietary driver will hopefully be quick to support tear-free PRIME, thanks in part due to their ongoing driver restructuring work that also is part of bringing up Wayland/Mir support.