Comment by dinckel@lemmy.world on The HDMI Forum rejected AMD's open source HDMI 2.1 implementation

DisplayPort already exists

We cannot have two standards, that’s ridiculous! We need to develop one universal standard that covers everyone’s use cases.

There are now three competing standards.

https://xkcd.com/927/

I know what you are referencing, but displayport already covers everybody’s use cases

Oh? Let me CEC on that…

I’ll just pull it up on this display that’s more than 9 feet away from the source…

#switchtodisplayport

Hi, my name is USB-C!

And what does that use? That’s right it’s Displayport Alternate Mode! Oh you’ve got Thunderbolt? Guess what, also Displayport!

Yes, I agree. And it needs to be open bloody source!!

Hard to find on non-pc gear, but that’s a fair point

It’s usually easy enough to adapt it as needed. It can typically send signals compatible with HDMI and DVI-D just fine.

The passive adapters that connect to DP++ ports probably still rely on this HDMI specific driver/firmware support for these features.

can’t you just mod it?

USB-C display output uses the Display Port protocol

Can it use others, and is there a benefit? USB C makes a lot of sense; lower material usage, small, carries data, power and connects to almost everything now.

I believe USB-C is the only connector supported for carrying DisplayPort signals other than DisplayPort itself.

The biggest issue with USB-C for display in my opinion is that cable specs vary so much. A cable with a type c end could carry anywhere from 60-10000MB/s and deliver anywhere from 5-240W. What’s worse is that most aren’t labeled, so even if you know what spec you need you’re going to have a hell of a time finding it in a pile of identical black cables.

Not that I dislike USB-C. It’s a great connector, but the branding of USB has always been a mess.

would be neat to somehow have a standard color coding. kinda how USB 3 is (usually) blue, maybe there could be thin bands of color on the connector?

better yet, maybe some raised bumps so visually impaired people could feel what type it was. for example one dot is USB 2, two could be USB 3, etc

Have you looked at the naming of the usb standards? No you havn’t otherwise you wouldn’t make this sensible suggestion.

Please think of the shareholders… :(

I think that the biggest issue with dp over usbc is that people are going to try to use the same cable for 4k and large data transfers at the same time, and will then whine about weird behaviour.

4K works for mine (it’s 3.2).

Yep, very true. I didn’t understand this until I couldn’t connect my Mac to my screen via the USB C given with the computer, I had to buy another (and order it in specifically). Pick up a cable, and I have no idea which version it is.

Yeah I have multiple USB cables, some at 30w, and some at 140w. Get them mixed up all the time! More companies need to at least brand the wattage on the connectors.

Dont forget the limited length. I cant remember exactly but usb c delivering power has a max length of arpund 4 metres

This is the big issue I have with with “USB C”. USB c is just the connector which can be used for so many things. What actual is supported depends on things you can’t see, like the cable construction or what the device supports.

There’s some really high bandwidth stuff that USB-C isn’t rated for. You have to really press the limits, though. Something like 4k + 240Hz + HDR.

That doesn’t even seem so unreasonable. Is that the limit though? My cable puts a gigabyte a second down it so I wouldn’t imagine that would hit the limit.

It is trivial arithmetic: 4.52403840*2160 ≈ 9 GB/ s. Not even close. Even worse, that cable will struggle to get ordinary 60hz 4k delivered.

USB-C with Thunderbolt currently had a limit of 40Gbit/sec. Wikipedia has a table of what DisplayPort can do at that bandwidth:

https://en.wikipedia.org/wiki/DisplayPort

See the section “Resolution and refresh frequency limits”. The table there shows it’d be able to do 4k/144hz/10bpp just fine, but can’t keep above 60hz for 8k.

Its an uncompressed video signal, and that takes a lot of bandwidth. Though there is a simple lossless compression mode.

USB C is just a connector, you might be referring to Displayport over USB C which is basically just the same standard with a different connector at the end. That or Thunderbolt I guess

I thought thunderbolt was DP passthrough as well

USB C seems like a good idea but in reality all it really did was take my 5 different, not interchangeable, but visually distinct, cables, and make them all look identical and require labeling

I love having mysterious cables that may or may not do things I expect them to when plugged into ports that may or may not support the features I think they do.

If the implementation is so broad that I have to break out my label maker, can we even really call it a “standard”

you mean thunderbolt?

Linux has very little to do with DisplayPort. My Windows PCs use DisplayPort. You can get passive adapters to switch from HDMI to DisplayPort etc.

The problem is those passive adapters only work because one side switches to the other’s protocol.

What exactly doesnt work over HDMI?

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