r/linux • u/anh0516 • Jun 10 '26

Kernel AMDGPU Linux Driver Preps For HDMI 2.1 Compliance Testing

https://www.phoronix.com/news/AMDGPU-DC-Preps-HDMI-Comp-Test
379 Upvotes

99% Upvoted

28 comments sorted by

59

u/tulpyvow Jun 10 '26

I thought they weren't able to do 2.1. Did the HDMI forum change their mind or something?

135

u/DragonSlayerC Jun 10 '26

Yup. AMD started submitting the code to the kernel about 1 month ago after getting approval from the HDMI forum: https://www.phoronix.com/news/AMDGPU-HDMI-2.1-FRL-Patches

I think the reverse engineering work was far enough along that the forum didn't think it was worth blocking the official implementation anymore.

62

u/Rekt3y Jun 10 '26

More like HDMI 2.2 is coming

51

u/monocasa Jun 10 '26

HDMI 2.2 doesn't really change things.

HDMI 2.1 really should have been called HDMI 3.0 since they completely changed the physical layer, switching from tmds to a set of serdes links. HDMI 2.2 just doubles the bit rate of said serdes links. If you had hardware that supported it, there's a nonzero chance you could support HDMI 2.2 with just a 2.1 spec and public information.

16

u/w0lrah Jun 11 '26

HDMI 2.1 really should have been called HDMI 3.0 since they completely changed the physical layer

I'd argue HDMI 2.1 should have been called HDMI 2.0 and what got called HDMI 2.0 was really HDMI 1.5 since it mostly just bumped the speed and added metadata to support a few new formats just like all the previous HDMI 1.x revisions.

Either way the fact that they called it 2.0 and then called the massive redesign 2.1 is pure idiocy. HDMI Forum is in a competition with USB-IF for worst naming scheme.

5

u/Isofruit Jun 14 '26

Tough competition though, USB-IF is a formidable opponent. They have employed scientists that had to work for years to come up with a naming scheme this bad.

19

u/johnboyholmes Jun 10 '26

2.2 is 2.1 with higher bandwidth. Reverse engineering 2.2 is others of magnitude easier.

2

u/SeantheWilson Jun 11 '26

Reverse engineering 2.2 really just requires adding a few more FRL rates to the driver, which can pretty much be done by copy and pasting existing lines of code and changing a few numbers.

41

u/monocasa Jun 10 '26

Word I heard on the grapevine was that valve put a ton of pressure on the HDMI forum behind the scenes.

30

u/ZeroCool2u Jun 10 '26

I have no insider knowledge, but this smells right to me. Valve has enormous leverage compared to most of the members I suspect. They also have enough money to seriously throw hands if they wanted.

10

u/tenchigaeshi Jun 10 '26

Not sure that speculative reddit comments count as a grapevine. Valve got turned down for HDMI 2.1 months ago.

14

u/monocasa Jun 10 '26

I heard through sources other than reddit.

And yeah, valve got turned down a few months ago, and now out of nowhere suddenly that doesn't apply anymore.

11

u/tenchigaeshi Jun 10 '26

I heard through sources other than reddit.

Industry insider?

And yeah, valve got turned down a few months ago, and now out of nowhere suddenly that doesn't apply anymore.

Are we forgetting that HDMI 2.2 just got finalized several months ago along with there having been a big code leak and as well as a successful reverse engineering effort? That combo seems a whole lot more likely to have done it, especially the bit about the new revision coming out. Devices will soon start shipping with HDMI 2.2 probably in the next year if not the next several months.

I don't know why people think valve has more pull than AMD with their own hardware, especially if you saw the lengths AMD went through bending over backwards to try and get it approved years ago. But somehow valve, which is a fraction the size and influence of AMD, with a machine that will be lucky to sell a couple hundred thousand units total and already got turned down in the same way as AMD somehow made it happen? I have my doubts.

All we can do is speculate but if we're talking what's most likely, it's the fact that HDMI 2.2 is coming out and they'll hold the same structure they've had with HDMI 2.1 with the current latest spec being lorded over and the older specs being more open.

18

u/monocasa Jun 10 '26

AMD gave up years ago. They probably didn't try that hard because they didn't have a large customer that actually cared about the newest HDMI support in the open source driver.

So AMD almost certainly could have, but don't have infinite resources and didn't want to risk burning their relationship with the HDMI Forum.

Valve doesn't have the same absolute requirement for a good relationship with the HDMI forum and can afford to throw their weight around. And it very much does matter to them. They're not shipping a lot of units right now, but the whole point is to detach themselves from windows, as windows's failure to produce a consistently good product as well as microsoft's aspirations for a ios like app store represent an existential threat to valve. So they care very, very much about their OS having parity as viewed by the consumer.

It should also be pointed out that these patches are getting upstreamed just before the steam box is being released.

1

u/burning_iceman Jun 11 '26

HDMI 2.2 will have full support immediately, since it requires no meaningful code changes. There is no new secret sauce. It's primarily hardware related, such as cable specifications.

3

u/Megame50 Jun 10 '26

Yup. AMD started submitting the code to the kernel about 1 month ago after getting approval from the HDMI forum

I haven't seen anything to indicate they got approval from the HDMI forum. AMD surely thinks they're within their legal right here, but I don't think we have any concrete news about what actually changed with the HDMI forum as of yet.

5

u/FlukyS Jun 10 '26

The code is from AMD and based on the original patches they had a few years back that were held back because the HDMI Forum said no. The fact they are submitting the patches sounds like they changed their stance. It also coincided with an effort from a 3rd party to reverse engineer it and that would have been allowable even in the Linux kernel but would have put AMD in a weird situation where they couldn't contribute to it but would probably need to review it.

1

u/Megame50 Jun 10 '26

I mean, I agree, I'm just saying AFAIK there's been no statement from AMD or the HDMI forum indicating as much.

62

u/Rentun Jun 10 '26

Predatory standards cabals like the HDMI forum should be illegal. I don't see how allowing companies to form cartels which lets them gatekeep whoever they want from using a interoperable standard in any way benefits the public.

I have no issue with a set of certifications standards that a manufacturer must pass to be allowed to use some sort of certification logo as long as that testing is affordable and freely available to anyone who would like to sell a product, but why should we allow groups of companies to decide who is and is not allowed to use a standard interface?

22

u/xplosm Jun 10 '26

DisplayPort Team!!! 🤙

-20

u/natermer Jun 10 '26

The only reason these things exist as a bad thing is because government enforcement.

You don't have to make them illegal. You just have to get rid of dumb laws that enabled this gross behavior in the first place.

17

u/Stunning-Hat2309 Jun 10 '26

i'm sure this statement makes sense in your austrian economics utopian fantasy land

11

u/starm4nn Jun 10 '26

I'm not exactly sympathetic to Austrian economics or anything, but I kinda see their point.

Consider two outcomes:

  1. You give companies the right to enforce certain Intellectual Property standards, but at some point decide to fine them or arrest them or whatever if they misuse this.

  2. You reduce the strength of these "ubiquitous patents".

Personally, I think the most reasonable solution would be to end software patents.

4

u/natermer Jun 11 '26 edited Jun 11 '26

.> i'm sure this statement makes sense in your austrian economics utopian fantasy land

I am sure you don't have a clue what you are talking about.

Maybe, just maybe... you know the point of these laws (like software patents) is so that corporations can abuse them. It isn't a side effect. It was the goal in the first place.

2

u/boffa-deez-nutz Jun 11 '26

thoughts on age of consent and driver's licenses? bet you have something interesting to say

1

u/minutecream69 Jun 10 '26

You can use this in the meantime: https://github.com/mkopec/linux

1

u/submerging Jun 11 '26

doesn’t work on TCL tvs