USB4 Specification v2.0

https://www.usb.org/document-library/usb4r-specification-v20

by cesarb • 4 years ago

44 58 4 years ago

usb.org

cesarb• 4 years ago

Announcement: https://usb.org/sites/default/files/2022-10/USB-IF%20USB%208...

Specifications released today:

- USB4 Specification v2.0 <https://www.usb.org/document-library/usb4r-specification-v20>

- USB Type-C® Cable and Connector Specification Release 2.2 <https://www.usb.org/document-library/usb-type-cr-cable-and-c...>

- USB Power Delivery Revision 2.0 Version 1.3 and Revision 3.1 Version 1.6 <https://www.usb.org/document-library/usb-power-delivery>

Yes, they really called it "USB4 v2.0"...

TylerE• 4 years ago

I’m surprised they didn’t call it USB4 SuperSpeed

Tozen• 4 years ago

That probably will still make it as a product name, somewhere.

Alupis• 4 years ago

Hardware revision numbering schemes can sometimes get wonky... but it's almost as-if the USB folks live in a bubble and are completely unaware of the meme their naming scheme has become.

There has got to be a more simple naming scheme that's easier to follow...

smesla• 4 years ago

it's almost as-if the USB folks live in a bubble and are completely unaware of the meme their naming scheme has become.

It's almost as if it was designed by a committee.

booi• 4 years ago

Hi, USB committee member here. I hear your concern and I’m officially launching the USB4 v2.0 naming schema v0.5b task force to analyze the naming schema. Thank you for your concern.

stingraycharles• 4 years ago

Semantic versioning would be just fine here I’d say; e.g. they could have named this USB 4.1 to indicate compatibility.

Alas, I suspect there are many conflicting desires here, and marketing may have something to do with it — the ability to convince customers into buying new hardware by confusing them may have something to do with it.

bryanlarsen5• 4 years ago

that name is the spec name, the marketing names have been cleaned up and are much more sane: https://arstechnica.com/gadgets/2022/09/usb-if-says-goodbye-...

mortenjorck• 4 years ago

When those products come out, though, the USB-IF hopes they aren't introduced to consumers as "USB4 Version 2.0" or even some type of "SuperSpeed USB." After 12 years, the USB-IF no longer recommends that vendors use terms like "SuperSpeed USB 20Gbps" (for the spec called USB 3.2 Gen 2x2, for example) and instead opt for names like "USB 20Gbps."
If the USB-IF had its way, products using its new open standard will be described as "USB 80Gbps."

Despite the ongoing chaos of USB-IF's technical nomenclature, it sounds like they are well aware of the problem, and the consumer-facing solution they recommend doesn’t sound bad at all.

guiambros• 4 years ago

More sane indeed; glad they realized it was completely non-sense. Thanks for sharing; the post you linked is actually much better than OP's link USB4 specs.

IshKebab2• 4 years ago

I don't think that's a great excuse. It's find for companies to have internal and external (marketing) names for the same thing, but these are both public! They have two public names for the same thing which is arguably even more confusing.

Look at that article:

The USB-IF still recommends vendors label USB 2.0, which can take the form of USB-C, USB-A, USB-B, and more, as "Hi-Speed USB" with no performance indicator. > "Hi-Speed USB has been around for over 20 years and is well established in the marketplace"

They are seriously under the delusion that anyone except USB nerds has even heard of "hi-speed USB".

throw0101c• 4 years ago

Revision 2.0 Version 1.3 and Revision 3.1 Version 1.6

WTF?

Ptchd• 4 years ago

Are we finally going to get a round connector?

djha-skin• 4 years ago

Does this mean I'll have to deal with another planned-obsolescence connector? I was hoping with Moore's law flattening out that we would more or less be done with this mess. USB-C does a great job, what's wrong with it?

nicoburns• 4 years ago

Pretty sure this is still using the USB-C connector.

chrisseaton3• 4 years ago

USB-C is a connector.

USB4 v2.0 is a protocol.

Different things. No need to be this excited.

stjohnswarts• 4 years ago

this is more than most non-techie people can handle.

drzaiusx11• 4 years ago

afaict it will still use the usb-c connector, they're just playing catch-up to thunderbolt as far as bandwidth. now you can do PCIe over USB4 just like thunderbolt. Although I haven't read the whole spec yet, likely it finally supports dual high-def monitors which USB4v1 didn't do

dymk• 4 years ago

Nah you'll have to wait for USB5 for the new connector

eyelidlessness• 4 years ago

Gonna disagree with all of the other comments so far: yes, you’ll have to deal with another set of USB-C connectors with a slightly different capability matrix.

nuker2• 4 years ago

Im certain it does not support USB 3 Gen 2x2 (20 Mbps) devices :(

Dylan168075• 4 years ago

Why? When have they ever dropped compatibility, and what would their motivation be?

nuker2• 4 years ago

Beats me, but that was outcome when I searched last time. It will support at 10 Mbps, not 20

derefr3• 4 years ago

What does the "4" in USB4 mean? When does it change? Why did it change fairly frequently until recently (with minor versions like 3.1), but then stop at 4?

I had always assumed the number in the name was the spec version. But now the spec version is explicitly v2.0, but the "4" remains in the name. Why isn't this USB5.0?

It's not like USB ports are labelled with what USB version they support or anything, such that there would be valid reasons to have a "compatibility version" that stays at 4. USB ports are just labelled/colored according to a marketing term that loosely maps to supported link speed (Hi-Speed / black, Super-Speed / blue, etc.)

Is this a thing like X11 (the "11" was a protocol version number once upon a time!), where the major version in the name somehow gradually ossified and became hard to change, even as major things kept happening to the spec; and so they just gave up and made the version an opaque part of the name, and lifted the version out somewhere else?

fabiospampinato• 4 years ago

It all makes sense once you understand that they are trying to confuse us as much as possible.

bryanlarsen5• 4 years ago

They 4 is meaningless and confusing. Which is why all version numbers are being dropped completely on labels and marketing. https://arstechnica.com/gadgets/2022/09/usb-if-says-goodbye-...

derefr3• 4 years ago

So, if the USB IF agree on that point, why isn't this spec just called "USB Specification v5.0"? Like when the Linux kernel dropped the 2.x/3.x and just started incrementing major versions with every major release?

wmf4• 4 years ago

Like anything, they have major versions and minor versions. USB4 was a new major version because it added Thunderbolt. USB4 2.0 (should have been USB4.1 but whatever) adds some minor changes.

chrisseaton3• 4 years ago

but whatever

I think people are asking - what really is the 'whatever' behind this version scheme?

rektide2• 4 years ago

USB4 moved from a lane-switched architecture to a packet switched architecture.

In USB3, for example, if you plug in a DisplayPort display via USB-C, there was an alt-mode negotiation, either 2 or 4 of the 4 lanes would switch over to become DisplayPort lanes (leaving you with either 2 or 0 lanes of USB3). Even if you have a 1080p60 (~4.3Gbps) monitor plugged in, you're still losing 20 of the 40Gbps because you're losing half the lanes.

In USB4, everything (except USB1 & USB2, lol) is tunneled over USB4. If you plug a hub in to a computer, and a display (or two or three) into a hub, the displays only take as much bandwidth as they need from the total link budget. Each 1080p60 monitor is taking 4.3 of the 40Gbps (or less, if the monitor has Display Stream Compression). Same goes for devices plugged in via PCIe/Thunderbolt.

There were a lot of weird architecture limitations because of the lane-switched architecture of USB3. It's more or less reason we almost never saw USB hubs with multiple USB-C ports: people would plug in a USB-C monitor, and maybe the hub could be smart enough for that, but plug in a second USB-C monitor, and now the DisplayPort lanes somehow need to serve two monitors. (This is actually achievable with DisplayPort's Multi-Stream-Transport hubs, but lack of support from Apple caused constant angst here.) With USB4 though, a hub can now just route packets, so you can imagine having multiple USB-C hubs fanning out & serving multiple displays; USB-C makes more sense now & has much less caveats under USB4.

augustuspolius4• 4 years ago

I like the USB-C connector but wondering if there is a better way to handle the ever expanding number of different cable types that are used with this connector (SuperSpeed, Thunderbolt, etc).

Switching to USB-C reduced the number of different cables I have at home but almost equally increased the number of different types of USB-C I have. Some work with my monitor, some don’t, some charge, some don’t charge, it’s a mess.

chrisseaton3• 4 years ago

If you want to, you can buy all 40 Gbps 240 W Thunderbolt 4 Pro USB-C cables for all use-cases, but they're literally like $100 a metre, so that'd be insane and why instead there's a variety of cheaper cables for different use-cases.

wmf4• 4 years ago

A USB-C 3.0 100W cable is more like $20 and does everything other than Thunderbolt. The OP must have really bad luck.

augustuspolius4• 4 years ago

Exactly - it's too expensive and at this point I am not sure how future proof this investment would be. Are we going to have a new USB-C cable in a year's time that my next monitor will require?..

Edit: different devices add even more to this confusion. My MacBook Pro M1 is refusing to work with a 4K USB-C monitor even when using a Thunderbolt 4 cable. LG is convinced that it should be working just fine.

Dylan168075• 4 years ago

Where the heck did you get a cable that can't charge? Unless you mean it can't go over 60 watts?

augustuspolius4• 4 years ago

Sorry, I meant data transfer+charging at the same time.

diebeforei485• 4 years ago

What exactly is USB4 2.0? Why isn't it called USB 4.1?

causality0• 4 years ago

Ok so what event happened after USB 3.1 came out that made the USB committee lose their damn minds? Everything made perfect sense until then.

MichaelZuo• 4 years ago

Looking forward to USB4.1-C 2.0 4x4 Revision 1.1

csense• 4 years ago

We once had a world where we didn't have to think very hard, and could use most cables with most devices.

How do we get back to that world?

USB4 Specification v2.0

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