AMD Adding Experimental Video Mode Optimization To FreeSync
At least under Linux AMD is currently working on a new and currently experimental video mode optimization for FreeSync.
Of this experimental feature they describe it as:
This patchset enables freesync video mode usecase where the userspace can request a freesync compatible video mode such that switching to this mode does not trigger blanking.
If experimental freesync video mode module parameter is enabled, add few extra display modes into the driver's mode list corresponding to common video frame rates. When userspace sets these modes, no modeset will be performed (if current mode was one of freesync modes or the base freesync mode based off which timings have been generated for the rest of the freesync modes) since these modes only differ from the base mode with front porch timing.
The feature while experimental is hidden behind the amdgpu.experimental_freesync_video=1 module option to activate.
For now this experimental AMDGPU FreeSync feature can be found in patch form via the mailing list.