853
The HDMI Forum rejected AMD's open source HDMI 2.1 implementation
(www.gamingonlinux.com)
This is a most excellent place for technology news and articles.
Linux has very little to do with DisplayPort. My Windows PCs use DisplayPort. You can get passive adapters to switch from HDMI to DisplayPort etc.
The problem is those passive adapters only work because one side switches to the other's protocol.