Atomic mode-setting and nuclear page-flipping have been talked about for years on Phoronix in numerous articles while the code is still being refined and readied for mainline inclusion.
For those wondering about what these terms mean -- and Rob Clark's Git branches with this work carrying "global-thermonuclear-war" titles -- Pekka Paalanen has written a lengthy and informative blog post for those wanting to do some educational reading.
Pekka's well-written article covers from the early days of Linux graphics drivers through the advent of KMS/DRM and Wayland and then the current work with universal plane support and the global thermo-nuclear patches. Pekka also covers the challenges presented by G-Sync and FreeSync technologies for the Linux graphics stack. The adaptive-sync standard will cause problems for the Linux graphics stack in its current form but is an issue that can be overcome.
You can read Pekka Paalanen's post in full via his blog.