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M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

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Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#51

Post by nicoburns »

maccard wrote: post #43
masklinn wrote: post #36

Earlier quoted context omitted.

> How about by using different ports? That would just be worse: the port being backwards compatible is a feature, being able to plug a 5Gbps device into a 20G-capable-port is a good thing, so is being able to plug a self-powered device into a PD-capable port. The issue is the difficulty of matching the cable with the device (and port) to ensure the upper bounds match. Obviously you could get the highest-rated cables…

> That would just be worse I disagree. In my cable/charger box I have 4 USB-c chargers with 4 USB-c cables, and they're not interchangeable for all intents and purposes. I've ended up sharpieing what device they belong to rather than reading the specs printed on the back of the charger, because otherwise I end up trickle charging devices (and thankfully I don't use a USB c dock, or I would be in all sorts of hurt. >…

A legal mandate that they had to be different colours where be the best way I think.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#52

Post by jsjohnst »

scoopertrooper wrote: post #47
mlindner wrote: post #2

My initial suspicion would be the user used bad cables. There's many cables that say they're capable of a speed when they are not in fact capable.

Why bother reading the article when you can just slam out hot takes? > Cables used included a certified Thunderbolt 4 model, and the USB-C (data) cables provided with the cases. Again, each was verified by establishing SuperSpeed+ 10 Gb/s connections to an Intel Mac.

Because we all know unnamed brand / model “certified” cables with drives that are also unnamed brand / model could surely not be the problem?

Edit: I did read the entire article. Like others have said here, it doesn’t match with my experience. But because nothing is clearly specified as to what’s used, the article is useless because nobody can compare to see if their setup is the same or different.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#53

Post by georgyo »

infinityio wrote: post #39
nikanj wrote: post #6

USB went from being the universal bus, to just being the universal connector. There are never any guarantees that your device (or cable!) actually supports the operation you’re trying

> (or cable!) Recently, I tried to find a Displayport-compatible cable and went through three (admittedly on the cheap side) cables that claimed to support it but didn't - in the end, I just bought a certified Thunderbolt 3 cable to avoid any ambiguity in whether they included all the wires or not

Wires is only part of them problem.

A thunderbolt 3 cable has two microcontrollers in the cable itself!

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#54

Post by floatboth »

Dylan16807 wrote: post #33
usrusr wrote: post #19

Earlier quoted context omitted.

But then you wouldn't be able to label-engineer your old chips into "the latest version" (of the old feature subset). Isn't "USB 3.1 Gen 2" the usb 2 performance level as (re)specified in the USB 3.1 document set? I'm deliberately writing without involving a search engine, to make my reply an authentic sample of the resulting confusion. My memory is probably wrong - and if it isn't, the lack of confidence still serve…

The generations start with USB 3.0. But for bonus confusion they don't refer to connection speed. They refer to single lane speed, and a connection can have 1 or 2 lanes. Gen 1 is 5Gbps, gen 2 is 10Gbps. Gen 2x2, sigh , is 20Gbps total. If they weren't trying to obfuscate things, those would simply be 3.0, 3.1 and 3.2. There's also Gen 1x2 in theory, but I've never seen mention of anything using it. And then after US…

So it's basically like PCIe now.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#55

Post by rileymat2 »

can16358p wrote: post #46
huhtenberg wrote: post #32

Earlier quoted context omitted.

Unless you are a disk drive vendor, in which case you insist it's 10.

Why? Assuming a byte being 10 bits instead of 8 bits would actually make the drive capacity lower in terms of bytes (of course not physically but for marketing), which a vendor probably doesn't want.

I am not sure what the op is talking about with bytes, but it could be powers of 2 v. powers of ten for kb/mb/gb.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#56

Post by tambourine_man »

woodruffw wrote: post #5

The inability of the USB standards body to stick to a versioning scheme beggars belief: what in the world could "USB 3.1 Gen 2" possibly mean? Versions are free, why not simply name it "USB 3.2" and make the next one 3.3? "Gen 2" strikes me as the "Essay FINAL (final version 2).docx" of standards revisions.

At least Wi-Fi folks seem to have taken a hint with Wi-Fi 6.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#57

Post by arcticbull »

tambourine_man wrote: post #56
woodruffw wrote: post #5

The inability of the USB standards body to stick to a versioning scheme beggars belief: what in the world could "USB 3.1 Gen 2" possibly mean? Versions are free, why not simply name it "USB 3.2" and make the next one 3.3? "Gen 2" strikes me as the "Essay FINAL (final version 2).docx" of standards revisions.

At least Wi-Fi folks seem to have taken a hint with Wi-Fi 6.

Didn't last long, haha, the new one is 6E.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#59

Post by TheRealSteel »

tambourine_man wrote: post #56
woodruffw wrote: post #5

The inability of the USB standards body to stick to a versioning scheme beggars belief: what in the world could "USB 3.1 Gen 2" possibly mean? Versions are free, why not simply name it "USB 3.2" and make the next one 3.3? "Gen 2" strikes me as the "Essay FINAL (final version 2).docx" of standards revisions.

At least Wi-Fi folks seem to have taken a hint with Wi-Fi 6.

They lasted less than a year before putting out Wifi 6E

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#60

Post by amelius »

masklinn wrote: post #41
RedShift1 wrote: post #8

Earlier quoted context omitted.

5 gigabit/s = 0.625 gigabyte/s = 625 megabyte/s so about 20% overhead... I would not be dissatisfied with 500 MB/s result on a theoretical 625 MB/s bus.

FWIW it's actually 500MB theoretical (ideal), because USB uses a 8/10 encoding[0], until 3.1 Gen 2 which switches to a 128/132 encoding[1]. So you have a 5Gb/s physical signal, then a 25% encoding overhead, for a raw data throughput of 537MB/s. Once framing and protocol overhead are taken in account, mid-400s effective is probably a good result. [0] https://en.wikipedia.org/wiki/8b/10b_encoding [1] https://en.wikiped…

What sucks, however, is that you can transfer 1TB to a USB drive correctly, and then finally have a bit-error that spoils the entire transfer and might even corrupt your drive. Happened to me several times during testing on different machines and with different cables and drives (luckily no real data was lost, but USB is now sort of banned from my office for use with external harddrives). Any sane protocol would be able to deal with such a low error rate, and finish a data transfer without problems.
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