AMD's open-source Linux graphics driver has hit a roadblock in adding HDMI 2.1+ due to the HDMI Forum's legal requirements. Despite lengthy attempts to find a solution, the HDMI Forum has rejected AMD's proposal, leaving users of some of the best graphics cards without the ability to use advanced features like 4K@120Hz and 5K@240Hz via HDMI 2.1. As a result, AMD recommends Linux users to switch to DisplayPort instead.
"The HDMI Forum has rejected our proposal unfortunately" said AMD Linux engineer Alex Deucher in a statement published in the bug report. "At this time an open source HDMI 2.1 implementation is not possible without running afoul of the HDMI Forum requirements."
For three years, AMD has been grappling with a bug report indicating the absence of 4K@120Hz and 5K @ 240Hz support through HDMI 2.1for Linux users. This occurred because in 2021 the HDMI Forum restricted public access to its specifications. This move was to ensure that only authorized manufacturers and developers can access the technical details required to implement HDMI features in their products (and pay royalties to developers of respective technologies). On the one hand, this move ensures the quality and consistency of HDMI experience. But on the other hand, this greatly hindered open-source driver support.
In response, AMD and the X.Org Foundation engaged with the HDMI Forum to devise a solution that would allow open-source implementations of the now-private HDMI specifications. AMD's Linux engineers, in collaboration with the company's legal team, dedicated months to evaluating all of the HDMI features to determine if they could be exposed in the open-source Radeon driver. They have reportedly developed internal code and awaited approval from the HDMI Forum.
Unfortunately, the HDMI Forum ultimately denied AMD's request for open-source driver support. The rejection is especially frustrating considering the months AMD spent engineering and prototyping code for HDMI 2.1+ features within its internal open-source AMDGPU codebase, notes Phoronix. This effort, aimed at showcasing HDMI 2.1+ capabilities for review by the HDMI Forum, now appears to be a largely wasted investment of significant resources.
In light of these challenges, AMD may need to explore alternative solutions, such as incorporating more features into its closed-source firmware or utilizing their PSP IP block to protect certain aspects of the HDMI specification. However, for the time being, the lack of HDMI 2.1+ feature support in open-source drivers remains reality. Consequently, open-source supporters are advised to use DisplayPort for the best experience.
