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DisplayPort standards bods school USB standards bods with latest revision

Video Electronics Standards Association shows the USB Implementers Forum how it's done

The USB Implementers Forum, USB-IF, rolled out the spec of USB 4 version 2 just last month, as you've probably read in The Register. We noted at the time that the nitty-gritty stuff would debut in time for developer events scheduled for November.

Well, it's nearly November, and a more detailed announcement [PDF] is here. (We especially like the _FINAL_v2 on the end of the filename. We've all done it.)

Apparently, if you have a passive USB-C cable capable of 40Gbps, with USB-4 v2 it will now be able to do 80Gbps. Good for you if you know the speed rating of your USB-C cables, because here at the Reg FOSS desk, we freely admit that we don't. We don't even know if ours are active or passive. We can only apologize for this wretched lack of professionalism, and once we learn how to tell, we'll put a new cartridge in our label-maker and rectify this.

Contrast this with the Video Electronics Standards Association's announcement of DisplayPort 2.1, which notes:

… all previously certified DisplayPort 2.0 products… have already been certified to the stricter DisplayPort 2.1 spec.

So if you have any DisplayPort 2 kit, relax, because it will still work fine with DP2.1 kit, which is how it should be.

USB-4 v2 will also encompass next-gen Thunderbolt.

However, forget about using older Thunderbolt devices on Thunderbolt 4 ports. They don't work, as per this note half way down the official Thunderbolt FAQ:

Accessories built to Thunderbolt and Thunderbolt 2 specifications are not supported by Thunderbolt 4 PCs.

Even if you buy a Thunderbolt 1 or 2 to Thunderbolt 3 adapter, it won't work on modern Intel kit:

solutions and products built to Thunderbolt and Thunderbolt 2 specifications will work with most Thunderbolt 3 PCs via an adapter, except Intel platforms launched in 2020 and later such as 10th gen Intel® Core™ vPro® platforms, 10th gen Intel® Core™ desktop and mobile processors.

Yes, Intel quietly dropped backwards-compatibility with the 10th gen Core chips. Thunderbolt, sadly, might add additional facilities to your USB-C port, but it won't work from any given generation to the next, which for all its vicissitudes is something USB generally excels at.

This isn't helped by issues such as Dell firmware updates breaking Thunderbolt support, as reported over and over and over and over again in the company's support forums.

USB-C is a mess, as was noted in 2018 and in 2020, and in 2022 it still is. Sadly, it is the best we've got. ®


In case you have any DisplayPort-to-HDMI cables around, a handy hint from the Reg FOSS desk: they are one-way. You can connect any HDMI display to a Displayport connector, but you can't connect a Displayport display to an HDMI connector. (Adapters do exist, but they're not cheap and are relatively bulky, active devices, so cheap cables won't do it.)

In contrast, HDMI to DVI works both ways: not only can you connect a new HDMI screen to a computer with the old DVI connector, but you can connect an old display with DVI to a new computer that only has HDMI, such as a Raspberry Pi.

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