PRIME Synchronization V3 was published earlier this week by Goins. He explains at the start of the 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 upstreamed 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.)"
This PRIME synchronization code amounts to just under 600 lines of new code while not taking into account the driver-specific changes. This work is particularly important for the laptops featuring both Intel integrated graphics and NVIDIA discrete graphics.
Goins also commented in this NVIDIA DevTalk thread, "It's hard to say how many revisions it will take before they are finally accepted, but hopefully it will be soon. Once the pieces land in their respective mainlines, and we release a driver to take advantage of it, I'll post here with a recipe for what versions of what software components are needed, if people want to try it out before the bits propagate to their distros. "