Just found promising discussion "4.6 DRM/i915 update CFT (Sandy Bridge?)/IvyBridge/Haswell/Broadwell/SkyLake/KabyLake supported".
http://lists.freebsd.org/pipermail/freebsd-x11/2016-May/017560.html
http://lists.freebsd.org/pipermail/freebsd-x11/2016-May/017560.html