Recently, it has been expanded why FreeSync support via HDMI does not reach the open source drivers, at least not yet … This stems from the decision of the HDMI Forum to open access to the HDMI specification, which in turn harms the open source -graphic drivers.
Since the HDMI specification is no longer public, but only “HDMI Adopters”, the support of the open source GPU driver is difficult. Even for those who are part of the HDMI forum, AMD in turn cannot provide an open-source implementation of features covered by the closed specification, to open up aspects of it potentially and indirectly to the public.
This situation seems to be the main blocking why FreeSync with the open source AMDGPU Linux kernel driver only works with DisplayPort and not with HDMI connections, which has consistently been one of the biggest questions regarding FreeSync Linux support and the current shortcomings.
The current HDMI specification constraints compromise many advanced HDMI features, such as HDMI 2.1, in the open source graphics drivers.
The X.Org Foundation calls on the HDMI forum to at least allow information about the HDMI 2.1 specification to be disclosed so that open source graphics drivers can in turn implement the features (legally).
Let’s hope it works out in 2021 … Keep that in mind when deciding on DisplayPort versus HDMI preferences!