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PayPalUnfortunately, the HDMI Forum refused to allow HDMI 2.1+ features in the open source driver, but that hasn't stopped one developer.
Writing in a Reddit post, the developer noted they've "successfully managed to implement HDMI FRL in AMDGPU, enabling full HDMI 2.1 bandwidth on your AMD GPUs" and they're now looking for testers. The code is up on GitHub, so anyone can take a look and see how it works.
From the Reddit post:
The current state:
- FRL training works
- Video and audio work
- HDR works, VRR
does notalso works- Hotplug, DPMS work
- Dynamic selection of the required FRL rate for a given mode is implemented
Caveats:
- Only DCN 4.0.1 (9070 XT) has been tested. Other GPUs should work similarly, but these paths are completely untested. There may be some clock dependencies there that I've not implemented or figured out yet. Hence me looking for testers today :) But do prepare for the possibility that the kernel might not even boot.
- Untested DCN generations include DCN 3.1 - DCN 3.6. DCN 3.0 (RX 6000 series) has not been implemented yet, but I believe it should be pretty similar to the newer DCNs.
- There is still some weirdness with my TV (Samsung S95B), where it will sometimes reject training higher FRL rates unless i restart the TV. So if you get no picture, try a lower resolution / refresh rate, or try restarting your TV.
- Support DSC is not implemented.
A murky legal situation though - as it's not entirely clear if the HDMI Forum can (or will be able to) block people going with a trial and error approach to getting more modern HDMI features working in the open source drivers. We know Valve have also been looking into certain features for the upcoming Steam Machine too.
Article taken from GamingOnLinux.com.
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but that hasn't stopped one developer.Sisyphus-ass dev. What a chad.
Quoting: syylkEnlighten me, LinuxHiveMind!Because you want to play Death Stranding 2, sitting on your couch in front of your 75" 4k 120Hz OLED Screen with HDR.
Sure, you could do this on a PlayStation 5, but this is GamingOnLinux, not GamingOnPlaystation...
Quoting: syylkDunno, but once you have DP or USB-C, why you'd want HDMI? Legacy? Enlighten me, LinuxHiveMind!If you use a TV screen as your gaming display (like I do, an LG OLED), DisplayPort or USB-C is rarely an option. Most of them only include HDMI inputs, which is a shame.
There are active DP1.4/USB-C -> HDMI 2.1 adapters that support the necessary features and transfer speeds, but I have no experience with them.
PS: In my experience, if you ask any Linux community about anything at all, you'll get at least two conflicting opinions, likely more. If there's a "LinuxHiveMind", it's got dissociative identity disorder or something.
Quoting: syylkDunno, but once you have DP or USB-C, why you'd want HDMI? Legacy? Enlighten me, LinuxHiveMind!Some people have existing hardware with HDMI input but no DP or USB-C, and very much would like to use it instead of trashing a thousand-dollar equipment because of "cable protocol forum is angry at this one dev".
Kinda the same reason people that moved to linux and uses nvidia hardware won't throw away their working card to get an AMD just because "it's the good way to do things".
Quoting: ShabbyXMy question is why HDMI is being such an ass?you asked the wrong question. The question is when is it Not being an ass.
(Yup, didn't think of TV gaming. 😁)
Quoting: LoftyNo I'm serious, what benefit does HDMI get from disallowing Linux supporting it?Quoting: ShabbyXMy question is why HDMI is being such an ass?you asked the wrong question. The question is when is it Not being an ass.
Do they want a member fee or something? If Valve wants this, paying for that on behalf of Linux seems like such an east thing, I couldn't believe that would be it.
Quoting: syylkThere are active DP1.4/USB-C -> HDMI 2.1 adapters that support the necessary features and transfer speeds, but I have no experience with them.I recently tried this [BENFEI DisplayPort 1.4 zu HDMI 2.1 Adapter](https://www.amazon.de/dp/B0GC5S8Q6C?ref=ppx_yo2ov_dt_b_fed_asin_title) with my LG G2 TV on Fedora43/LinuxMint/Ubuntu26.04 and had no success with VRR (FreeSync). I thought that maybe the sound would be transmitted in 5.1, but I didn't spend much time messing around with it. I sent the adapter back four days later.
Quoting: ShabbyXCollecting patent fees, royalties & restrictions etc.. Remember HDMI is not FOSS, it's not part of VESA afaik. Personally i think Displayport should be included on all TV's aswell but i would imagine the HDMI group leans hard on Samsung, Sony against using an alternative connector ?Quoting: LoftyNo I'm serious, what benefit does HDMI get from disallowing Linux supporting it?Quoting: ShabbyXMy question is why HDMI is being such an ass?you asked the wrong question. The question is when is it Not being an ass.
Do they want a member fee or something? If Valve wants this, paying for that on behalf of Linux seems like such an east thing, I couldn't believe that would be it.
I believe that's why we saw Apple using alternate connectors so they didn't have to pay the royalties associated. If wireless video streaming @ 60ghz ever becomes the norm we might not even need HDMI at all.
Last edited by Lofty on 18 Feb 2026 at 2:20 pm UTC
Quoting: ShabbyXDo they want a member fee or something? If Valve wants this, paying for that on behalf of Linux seems like such an east thing, I couldn't believe that would be it.AFAIK the spec is proprietary, secret, and must be licensed, as they nixed AMD's request to do a FLOSS implementation: https://www.gamingonlinux.com/2024/02/the-hdmi-forum-rejected-amds-open-source-hdmi-21-implementation/
Gerarderloper 2 minutes ago
Quoting: GreoYou need to firmware patch the adapters to get VRR and all the features working. And some adapters don't play as nice as others.Quoting: syylkThere are active DP1.4/USB-C -> HDMI 2.1 adapters that support the necessary features and transfer speeds, but I have no experience with them.I recently tried this [BENFEI DisplayPort 1.4 zu HDMI 2.1 Adapter](https://www.amazon.de/dp/B0GC5S8Q6C?ref=ppx_yo2ov_dt_b_fed_asin_title) with my LG G2 TV on Fedora43/LinuxMint/Ubuntu26.04 and had no success with VRR (FreeSync). I thought that maybe the sound would be transmitted in 5.1, but I didn't spend much time messing around with it. I sent the adapter back four days later.
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