[fps_doug]

> AMD obviously needs to license the logo for their GPU boxes

This poses an interesting question, maybe some of the hobby-lawyers on HN like to chime in and post heir theories :o)

Let's assume they print that Logo on their box, call it HDMI in their Windows drivers, but don't do so in their Linux drivers, while it's still a spec-compliant implementation. Would that pose a potential legal problem, and if so why?

If it's the fact that they have access to the official HDMI 2.1 spec, implemented that, but call it something else, which I could imagine they forbid in some contract, would things change if some random hacker with too much time on their hands reversed the protocol by sniffing it, implementing it for the AMD driver (again without calling it HDMI)?

Too bad the HDMI forum doesn't feature an email address on their home page, I'd have loved to tell them what I think of them.

[megous]

You don't just sniff a 48Gbit/s protocol as a random hacker. That's not what happens in the real world. A real-time scope that could do that is in the $1mil dollar range.

At best a random hacker will reverse engineer the binary driver enough to make something work in some capacity.

[CuriousCosmic]

Yes you actually can. It's known that HDMI is TMDS and that the fastest frequency on any given pair is 680MHz and there are a total of 13 data pins (4 pairs + i2c + CEC pin + hot plug detect pin + reserved pin for some special features). A digital logic analyser that can sample at that rate over all 13 pins is going to cost less than a grand. If you stub in some hardware to convert the differential pairs back to a single hi/low signal and drop the optional features of the reserved pin, you can cut that down to 8 signals (or less if your analyzer has dedicated clock signal pins). A DSLogic U3Pro16 is 299usd and can sample 8 signals at 1GHz in buffer mode or 3 pins at 1GHz indefinitely in streaming mode.

If you know roughly what you are looking for, you can set triggers to start sampling when the event you care about starts, that's more than enough to be able to reverse engineer even the most intensive of the existing HDMI spec.

Given that a lot of these graphics cards cost substantially more than 300usd, it's not unreasonable to expect a logic analyzer capable of digesting HDMI to be within their price range.

[ZiiS]

A lot of those $1mil dollar scopes run Linux and connect to fast, high resolution displays; some of them are made by companies not always in love with US licensing.

[fps_doug]

Sure, but this is a hypothetical scenario, focusing on the legal aspects.

[megous]

Legal aspects of something that can never happen? Why?

Try legal aspects of reverse engineering a binary driver. That's more realistic.

[iforgotpassword]

But the question is not whether it's legal to reverse engineer a binary. The question is whether someone with no affiliation to neither the HDMI forum nor AMD could contribute the according code to the AMD driver which is part of the Linux Kernel, regarding legal implications.

Reverse engineering of binaries is pretty much a solved problem from the legal standpoint.

[fps_doug]

It's hypothetical. There is no difference between those two scenarios, we could also just assume the hacker pulled it out of their ass...

[megous]

Fine, but it's useless then.

[Pet_Ant]

I mean a $1M is crowd sourceable if there was a trustworthy person to do this.

[ZiiS]

There is a contract between AMD and HDMI Forum covering the licence to use the logo. We don't know the wording, and I am sure it is thousands of pages of dense legalise; but it can literally say: "We promise not release a Linux driver compatible with the spec.".

[mschuster91]

> Too bad the HDMI forum doesn't feature an email address on their home page, I'd have loved to tell them what I think of them.

They actually do at the bottom of [1].

[1] https://hdmiforum.org/about/

[luke-stanley]

Thanks, I emailed them: # Solutions for the growing open source user base "Hello, I am an AMD user, who uses Linux, and I currently use a small HDMI screen but I am looking to upgrade to a larger screen and I am concerned about the forum's decision to deny AMD's open source HDMI implementation. This decision has led to criticism of the entire HDMI enterprise as rent-seeking, and encourages non-trademarked implementations that weaken the HDMI brand. Linux is only growing in popularity, as people are tired of the advertising baked into Windows, and don't always want a Mac either, I highly suggest a re-think that looks at the rising popularity of open source with Linux, Android, Chrome and so on, to protect the HDMI brand.

Sincerely, Luke Stanley"