HDMI Forum rejects AMD's HDMI 2.1 open-source driver

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No 4K@120Hz and 5K@240Hz via HDMI 2.1 for Linux users with Radeon.

HDMI plugging into laptop port
(Image credit: Shutterstock)

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.

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Anton Shilov
Anton Shilov
Contributing Writer

Anton Shilov is a contributing writer at Tom’s Hardware. Over the past couple of decades, he has covered everything from CPUs and GPUs to supercomputers and from modern process technologies and latest fab tools to high-tech industry trends.

71 Comments Comment from the forums
  • ThomasKinsley
    I anticipate a lone wayward AMD engineer will 'leak' the driver, against all orders from AMD, of course, and anonymously so they cannot find out who it was.
    Reply
  • snemarch
    Yet another reason to abolish HDMI and only purchase DisplayPort-capable hardware.

    Greedy royalty rent-seekers and Digital Restrictions Management supporters should be shipped off to Siberia.
    Reply
  • ezst036
    This is one of those things that through-no-fault-of-their-own advertently or inadvertently ends up holding back open source.

    *Boots to black screen* "Well it works on Windows, so I don't want to use Linux. None of this junk works."

    "But works just fine on Windows or my Mac" Yes, but it's not that the driver makers could not figure out how to do it, didn't have the time to do it, etc etc.

    "Well, it doesn't work." &%@##!

    It's the continual fight against both the chicken and the egg at the same time. AMD are trying to "do the right thing" here. HDMI forum are plain and simply saboteurs. The industry is fraught with them from this standpoint.
    Reply
  • Zaranthos
    ezst036 said:
    This is one of those things that through-no-fault-of-their-own advertently or inadvertently ends up holding back open source.

    *Boots to black screen* "Well it works on Windows, so I don't want to use Linux. None of this junk works."

    "But works just fine on Windows or my Mac" Yes, but it's not that the driver makers could not figure out how to do it, didn't have the time to do it, etc etc.

    "Well, it doesn't work." &%@##!

    It's the continual fight against both the chicken and the egg at the same time. AMD are trying to "do the right thing" here. HDMI forum are plain and simply saboteurs. The industry is fraught with them from this standpoint.
    True. On the bright side at least some companies are trying now. I read articles like this and make a mental note, go display port for all hardware and stay away from HDMI whenever possible. It only hurts the HDMI spec in the long run, but there is collateral damage to open source along the way like you said. I also watch and see AMD putting in real $ and effort to support open source so I'll buy their products as well. This from someone who barely uses Linux but still wants the option to.
    Reply
  • kanewolf
    So, AMD pays fees for their Windows driver, but won't pay fees for the open source?
    Probably not the case.
    OR was their open source driver rejected because it gave away too many of the proprietary details that AMD had reverse engineered ?
    My guess is the latter.
    Reply
  • setx
    kanewolf said:
    was their open source driver rejected because it gave away too many of the proprietary details that AMD had reverse engineered ?
    AMD bought the license, they didn't reverse-engineering anything.
    But they can't publish the code because it would "leak information" on that proprietary garbage.
    Reply
  • thisisaname
    HDMI is dead long live Display Port!
    Reply
  • kanewolf
    setx said:
    AMD bought the license, they didn't reverse-engineering anything.
    But they can't publish the code because it would "leak information" on that proprietary garbage.
    Just like other "open source" drivers, there are some parts that are only released as compiled binaries. WIFI radio drivers are this way to comply with the FCC, for example.
    Reply
  • Order 66
    thisisaname said:
    HDMI is dead long live Display Port!
    It's a shame that TVs don't use DisplayPort though. If you want to use a tv as a monitor, you have to use HDMI.
    Reply
  • Joseph_138
    ThomasKinsley said:
    I anticipate a lone wayward AMD engineer will 'leak' the driver, against all orders from AMD, of course, and anonymously so they cannot find out who it was.
    AMD would still be held responsible for the leak, and be sued. They have a duty to lock down the driver, now that they've been told not to release it, and failure in that duty will result in a lawsuit, even if a lone employee takes it on themselves to release it, anyway.
    Reply