[klempner]

> Not USB-C complexity

3.2 Gen 2x2 (and the occasionally relevant 1x2 if you have a weak cable) are USB C only.

USB C ports and cables have 4 USB 3 "superspeed" lanes rather than two. When you use an A to C cable only one pair of those connects. The point of the "x2" modes is that they use the second pair of lanes that would otherwise go unused.

Except of course they don't always go unused. DisplayPort Alternate Mode sends DisplayPort over those two "unused" lanes getting you USB 3 data alongside a half speed DisplayPort connection. (or alternatively full speed DisplayPort on all four and only USB 2), and then of course Thunderbolt 3 and modern USB4/TBT4 use all four lanes and tunnel everything.

[Carioca]

> The point of the "x2" modes is that they use the second pair of lanes that would otherwise go unused.

Thank you for answering a question I didn't know I had

[arghwhat]

Hmm, yes I was conflating a few things there.

However, I'd hold that this is an extension of the USB 3 mess that predates USB-C, even if the x2 mode specifically was a USB-C addition.

The important thing for people to know is that support for USB 3.2 Gen 2x2 is practically non-existent: TB3 came before as a well-established (but premium) solution, and USB4 just two years after to commoditize it. A complicated solution with mid-tier bandwidth and none of the flexibility didn't attract attention, so support is poor.

[klempner]

I mostly agree with you -- 2x2 is a relative rarity, especially before Intel's Barlow Ridge chipsets that actually added 2x2 support.

Which leads to the funny point that, as far as I am aware, the very first 2x2 capable hub chipset was USB4v2/TBT5 that happened to also support 2x2.