Thunderbolt 5 supports 20Gbps USB 3.2x2 tunneling, however, it's optional. Does anyone know if the M4 Pro's T5 implementation supports it? If no one does, I'll be testing it out on a Macbook tomorrow and I'll answer my own question.
Mac mini (M4)
So I received a more comprehensive response from Intel. It seems to that a Thunderbolt 4/5 port will support 3.2x2 if it’s implemented natively on the system. If the native USB implemented by the SOC doesn’t support 3.2x2, neither will the Thunderbolt port. Basically, Thunderbolt is just handing off to the native USB.
As Apple’s USB seemingly doesn't support USB 3.2x2, neither will its Thunderbolt ports. Also, there is no physical impediment/incompatibility to implementing USB 3.2x2 over any Type-C port.
Hence, it seems I was basically correct in my assumption that this is an omission by Apple, not Intel.
So I received a more comprehensive response from Intel. It seems to that a Thunderbolt 4/5 port will support 3.2x2 if it’s implemented natively on the system. If the native USB implemented by the SOC doesn’t support 3.2x2, neither will the Thunderbolt port. Basically, Thunderbolt is just handing off to the native USB.
As Apple’s USB seemingly doesn't support USB 3.2x2, neither will its Thunderbolt ports. Also, there is no physical impediment/incompatibility to implementing USB 3.2x2 over any Type-C port.
Hence, it seems I was basically correct in my assumption that this is an omission by Apple, not Intel.
Bummer. Just tried five different USB 3.2x2 SSDs and they all perform at 10Gbps speed, not 20Gbps. Really Apple?
Intel finally got back to me on this. Alas, the email wasn’t specific in its USB terminology (thinking perhaps that I knew all the USB specs by heart), but the way I read it this may be their doing. What they said is that any USB device connected to a Thunderbolt 5 port uses the straight USB protocol (apparently not including 3.2x2 which uses two extra data lanes). If however a dock is connected, it uses the USB4 spec tunneling and could feature a 3.2x2 port that uses the tunneling protocol.
So I’m thinking it may simply be impossible for Apple to implement support for 3.2x2 directly connected to a Thunderbolt 5 port. I suppose a vendor could include firmware on a drive that would tunnel, but I’m not sure how or how difficult that would be.
Having not heard from Apple after direct inquiry, I’m not going to bother apologizing to them. Please don’t take this as fact, this is my interpretation of an email that didn’t spell out everything in fine detail.
From what I've read, USB4 defines three different and incompatible "up to 20 Gbps" USB transfer modes.
Two of them are new, and at least one (which has the marketing name "USB4 20 Gbps") is mandatory for USB4 host ports. USB 3.2 Gen 2x2 is optional for USB4 host ports.
Can you say "thrown under the bus"?
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Thunderbolt 4 may introduce new wrinkles for devices connected via Thunderbolt 4 hubs and docks. I just came across this article, and was surprised to read that with current chipsets, Thunderbolt 4's hubbing ability comes at this non-obvious cost.
Other World Computing – Blog – What’s the Difference Between Thunderbolt 3 and Thunderbolt 4?
"Because of the difference in how Thunderbolt 4 allocates data, every port on a Thunderbolt 4 device that isn’t Thunderbolt must share a single 10GBps slice of USB bandwidth."
So theoretically, that might mean that
As for Thunderbolt 5, I don't have enough information to say.
Between this and having to ditch my Thunderbolt 2 audio interface (I think… it might work with the 2/3 adapter off a dock) I’ve kind of soured on the M4 Mini. Even if it does turn out to be Intel’s fault on the 3.2x2.
Note that it is NOT the case that you can’t use old Thunderbolt 2 stuff on Thunderbolt 5. I was told this by someone, and thought I’d read adapters weren’t supported, but I was just able to use my Thunderbolt 2 Clarett 4Pre on a new Macbook Pro’s Thunderbolt 5 port using the Apple Thunderbolt 2/3 adapter. Yay!
yes, BUT:
That ThunderBolt-3 <-> ThunderBolt-2 adapter supports ONLY genuine ThunderBolt devices on each side, and does not pass power. if you try to use that adapter with non-ThunderBolt devices, nothing happens.
Not sure what you mean by genuine, but it’s always been true that the adapter doesn’t pass power. I didn’t have a AC-driven Thunderbolt 2 dock with me to test, but that’s always been necessary if you want to run a bus-powered Thunderbolt 1/2 SSD post-adapter. I’ve never tried other devices like HDMI displays or USB peripherals post adapter, but I think if I can find one of these docks (I’ve hidden them somewhere as I’ve no need on my newer Mac Studio) I shall.
Also, I’m just happy my audio interface still works! I can grab an M4 Pro Mini and not have to upgrade!
BTW, I’ve tried several times and several ways to contact Apple (I write for Macworld, so you’d think…) about this, but nary a peep. Intel’s PR guys says I’ll likely hear post holidays. Everyone takes this week off now, which sucks for journalists.
<< Not sure what you mean by genuine [ThunderBolt devices]... >>
MANY users think their drive enclosures are ThunderBolt devices, because of Hype from the makers or sellers, when they are merely USB-C v3 devices.
So they buy this US$50 adapter, connect them up, and ... nothing happens.
USB and Type-C/USB-C are indeed very confusing for some users and certain journalists and marketing folks have further muddied the waters. Thunderbolt using the same type of port and connector certainly doesn’t help. There’s nothing for that other than reading fine print and doing your homework.
When you said genuine, I extrapolated sideways to fake, i.e. falsely advertised. But I haven’t seen any vendors claim their Type-C USB products are Thunderbolt. Maybe there are, and I just haven’t seen them.
Further confusing the picture… There were third-party adapters that were unidirectional — allowing you to connect T2 devices to T3 Macs, but not allowing you to connect T3 devices to T2 Macs.
Grant Bennet-Alder wrote:
<< Not sure what you mean by genuine [ThunderBolt devices]... >>
MANY users think their drive enclosures are ThunderBolt devices, because of Hype from the makers or sellers, when they are merely USB-C v3 devices.
Apple likes to call the USB-C ports on Macs Thunderbolt ports or USB4 / Thunderbolt ports whenever they can, to emphasize the higher-end features of these ports that aren't always present on any old USB-C port.
A lot of accessory vendors, especially on places like Amazon, throw around around terms such as Thunderbolt or Thunderbolt-compatible loosely when describing
This leads many customers to believe that they are using, or require, Thunderbolt devices, when the logic is really more along these lines:
jonljacobi wrote:
Further confusing the picture… There were third-party adapters that were unidirectional — allowing you to connect T2 devices to T3 Macs, but not allowing you to connect T3 devices to T2 Macs.
https://www.macworld.com/article/233893/how-to-use-any-thunderbolt-device-on-any-thunderbolt-macand-we-mean-any.html
The StarTech adapter is one of those.
It has the same limitation as the Apple Thunderbolt 3-to-2 adapter as far as not being able to present a "plain" DisplayPort signal on the Thunderbolt 2 side. It has the additional limitation of being unidirectional. You cannot use it to connect a powered Thunderbolt 3 dock to an older Thunderbolt 1/2-equipped Mac.
The price on the StarTech site ($35.99 USD) is much more reasonable than the prices which people are trying to get for it on Amazon ($55.55 – $167.67), all of which are higher than the price of the bidirectional Apple adapter!
Part of the problem is calling it USB-C. I don’t think that really became official until way after the press and marketing types started referring to is as such. I always refer to it as a Type-C connector then list the main supported transport protocol. E.g., Type-C Thunderbolt 3 port, or 20Gbps Type-C USB port, or 40Gbps Type-C USB4 port. Or a 5Gbs Type-A USB port. Yada, yada.
The USB-IF are jackasses when it comes to naming conventions. Only micro memory cards are more confusing.
I was just looking at a UGreen USB4 enclosure for review and the description was indeed confusing. However, they listed the bridge chip/controller so I could verify that it was actually USB4 that way.
jonljacobi wrote:
Not sure what you mean by genuine
I think he means that
In both cases, the issue would be that the connectors physically fit, but that the provided signal type does not match up with the needed one.
Now you could plug the TB2 side into a powered TB1/2 dock, and then Mini DisplayPort displays hanging off the old dock might work. Or plug the TB3 side into a powered TB3/4 dock as a way of being able to add a docking station to an old Mac for which new TB1/2 docks are no longer available. Then, the dock would be taking on the burden of implementing other stuff using the Thunderbolt or Thunderbolt-encapsulated DisplayPort signal.
But the basic takeaway is that just because the adapter has a "USB-C" plug and a "Mini DisplayPort" socket does not mean that it will speak any protocol on these connectors except Thunderbolt. So only a genuine Thunderbolt device will be able to work with the adapter successfully.
Does the M4 Pro Thunderbolt 5 implemenation support USB 3.2x2?
