AMD FreeSync HDMI Patch Appearing For Their Open-Source Linux Driver
HDMI 2.1 has Variable Refresh Rate (VRR) as part of the standard for reducing lag, stuttering, and frame tearing particularly while gaming. While HDMI 2.1 has the standardized VRR and many other features, HDMI Forum limiting specification access and what can be supported by open-source drivers has for now led to the lack of support there among the open-source Linux graphics drivers. The X.Org Foundation is trying to get the HDMI Forum to change course to allow for better open-source support, but anyhow what we are seeing with patch work that came out on Friday is for AMD's vendor-specific FreeSync with pre-v2.1 HDMI.
There finally is a patch adding support for FreeSync HDMI to the DC "Display Core" and DMCU (Display Micro Controller Unit) with the AMDGPU kernel driver.
It's not clear if it's all complete yet, but at least with the newest DC patches it's clear that FreeSync HDMI support is finally being worked on at least for pre-2.1 support for displays explicitly advertising AMD FreeSync capabilities. The timing though won't have this work coming to Linux 5.12 but hopefully it will get buttoned up in time for Linux 5.13 this summer. Prior to that it will likely work its way as well into AMD's packaged driver offerings.