Support Displayport mst

There's no issue with increasing resolution. Windows running on the same Mac hardware works perfectly with daisy chained display port screens.

Most monitors and docs that contain USB-C hubs use MST to connect a second display - these simply do not work with any device running macOS. The only reason is that apple haven't cared to implement MST in their driver software.

If you want to be able to put down your MacBook, plug in a single cable and have all your screens working then you have to buy a separate hub with 2 display ports, and it has to be an expensive one which specifically does not use MST internally. (Try CalDigit)

Complain to Apple, but they are unlikely to listen but you should complain anyway.

That is not a productive counter argument.

There is no need for aversion to a certain feature, only because some other OS supports it. We should strive to make any product the best it can be, and this being a software feature as pointed out by Mike, should be easy enough to implement.

Mac does infact not support any version of MST. Even thunderbolt monitors have to go 1 per port. (Atleast my research seems to point to this conclusion) and any docks that support multiple monitors, either take up multiple ports or rely on displaylink.

I can't think of a more Apple feature than 1 cable for *all* your connectivity needs, which is what a dock provides for many people.

DisplayPort 1.2 is limited to 17.28 G bits/sec, the amount needed for ONE "4K" hi-color display "4k" at 75 Hz.

Supporting MST would mean only small displays could jam their data on to that shared link, before it was completely saturated.

Apple has made the technical decision NOT to support that feature. My speculation is that is because it has limited usefulness.

You are welcome to complain the them. Here is the link:

Product Feedback - Apple

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So if I understand this correctly,

Apple sells a MacBook Pro that has USB-C ports that support the Thunderbolt protocol (3 or 4, depending on MBP) and USB protocol (3 or 4).

Both of these protocols can incorporate the DisplayPort protocol.

These USB-C ports work correctly and support all of the standards that Apple claims that they do, including DisplayPort MST, HOWEVER, macOS does NOT support DisplayPort MST (at least not over the USB protocol).

This means that running Windows on the MacBook Pro computer does takes full advantage of the DisplayPort MST via USB protocol and the problem is not with the MacBook Pro or the USB-C ports, but rather with macOS and the software support for DisplayPort MST via USB protocol?

Is this Correct?

Can anyone verify that a dock using Thunderbolt protocol can support DisplayPort MST?

I believe the problem lies with many companies selling docks and stating that they a "USB-C" dock, but not clarifying which protocol they are using.

Ex. Anker 575 USB-C Docking Station (13-in-1)

https://us.anker.com/collections/hubs-and-docks/products/a8392?variant=37438617944214

They state that "macOS only supports Single-Stream Transport (SST) and doesn't support Multi-Stream Transport (MST)"

This dock appears to use the USB protocol, however it is not clearly stated.

CalDigit TS3 Plus Dock

CalDigit TS3 Plus Dock - Apple

They state that "Whether you need to connect dual 4K 60Hz monitors* or a single Thunderbolt 3 5K 60Hz monitor, the TS3 Plus offers next-level visual fidelity.

External dual display support requires a Mac with an Intel processor and Thunderbolt 3 ports.

*The TS3 Plus supports dual 4K displays from either the DisplayPort port (which requires an active adapter if converting to other video interfaces such as HDMI) or the Thunderbolt 3 port (compatible with USB-C video adapters such as HDMI, VGA, or DisplayPort)"

This is a Thunderbolt dock, however it only has one DisplayPort connection and the other display needs to use the USB-C port to connect the display.

I have a CalDigit "USB-C Pro Dock" dock which connects via a single USB-C cable and has 2 HDMI ports. I've connected 2 2560x1440 screens and they work perfectly along with the inbuilt Retina display. The trick is that dock doesn't use display port MST - it makes the 2 screens appear as 2 separate "Thunderbolt/Displayport" connections.

Same amount of data over the same cable but in a way that macOS supports.

The dock built into one of the screens should do the same job but because it uses DP MST it's useless. Hence the need for an extra box and extra power supply on my desk.

It's not the most serious thing in the world but it does just seem stupid.

Like the option to airplay from my mbp to my tv that seems to have disappeared in one of the recent upgrades (yes I've checked the display settings - there's no airplay option there). I had to get a really long HDMI cable to watch anything that's only aired on paramount (and therefore not in the UK). Surely airplay is a software only feature - isn't it?

Sure here is one example. You can find displayport listed under the technical specifications of almost every apple laptop and desktop.

MacBook Pro (14-inch, 2021) - Technical Specifications

"Three Thunderbolt 4 (USB-C) ports with support for:

• Charging
• DisplayPort
• Thunderbolt 4 (up to 40Gb/s)
• USB 4 (up to 40Gb/s)"

As well as "Native DisplayPort output over USB‑C"

MST is part of DisplayPort. You cant have DisplayPort without MST. So unless the laptops support MST, that line item for DisplayPort is factually incorrect.

Whats worse is the physical hardware does in fact support MST, you can load up bootcamp (on non-m1 machines), and MST functions correctly. This is entirely a software issue with OSX/MacOS.

Macs have only ever supported MST to a genuine Thunderbolt Display as the first display. The second display can be whatever is supported by your first display..

Thunderbolt has two sets of data pathways to support more than one display -- DisplayPort has only one, so with the ever-increasing resolutions of displays, MST over DisplayPort is not of any practical value in the long run.

JeremyWorkAccount wrote:

I think the gripe is that MST support for two 1080P monitors (like in work contexts/hotel cubes) isn't going to saturate anything. Windows loaded on the same Mac hardware works just fine.

Additionally, if you didn't think this was a market that needed addressing look no farther than StarTech. They've got docks that support multiple monitors BUT you have to load their displaylink drivers which aren't HDCP enabled and basically push the display over USB even though you're using the same USB-C cable. I'm using a Startech doc that only supports one 'native' display via HDMI, and the two Displayport connectors only work via USB/VGA/Displaylink goofyness.

From a usability perspective this is ridiculous. It doesn't matter what the 'working as designed' quip might be. It is not unreasonable for users with multiple monitors like two 1080P monitors to be hooked up without goofy solutions.

<< Windows loaded on the same Mac hardware works just fine. >>

--> Then use Windows if that is the most important feature for you.

Using two cables to support two external displays is not a goofy solution, it is NORMAL.

Expecting the limited bandwidth of a DisplayPort cable to support TWO displays -- now THAT's goofy. If you want that, get a Thunderbolt-connected docking station.

...and since that MST-over-Displayport solution ONLY is possible when your two external displays are very modest sizes, Apple has chosen not to provide it as a general solution.

Apple does support MST -- Just not over DisplayPort.

MST is supported for genuine ThunderBolt devices, ONLY.

I think the gripe is that MST support for two 1080P monitors (like in work contexts/hotel cubes) isn't going to saturate anything. Windows loaded on the same Mac hardware works just fine.

Additionally, if you didn't think this was a market that needed addressing look no farther than StarTech. They've got docks that support multiple monitors BUT you have to load their displaylink drivers which aren't HDCP enabled and basically push the display over USB even though you're using the same USB-C cable. I'm using a Startech doc that only supports one 'native' display via HDMI, and the two Displayport connectors only work via USB/VGA/Displaylink goofyness.

From a usability perspective this is ridiculous. It doesn't matter what the 'working as designed' quip might be. It is not unreasonable for users with multiple monitors like two 1080P monitors to be hooked up without goofy solutions.

Sadly its a spec that apple doesnt have the technical ability to support. If you need advanced tech like this, your only option is Windows, Linux, BSD, ChromeOS, Android or quite literally every embedded OS that supports displayport.

It is of incredible value in the long run. Most docks work on display port MST. The ones that don't work on display link, which runs as a process and has to process everything making the entire OS lag when graphics intensive tasks are being run.

The draw calls aren't going to the GPU anymore, but rather to the extension.

While I agree MST is a desired feature unless Apple picks up the slack for peripherals that are available from other manufacturers, the thunderbolts specification kinda sucks in this regard. Thunderbolt 3 and 4 leave things open to future innovation. MST is one of those things that is an extension on Thunderbolt 4 and not part of the base specification.

So no, Apple doesn’t have false advertising, but I spent over 4k on a max, and the fact that I can’t use some thunderbolt accessories or mst over my usb ports is frustrating.

Rather than buy a windows machine perhaps we can request the engineers over at apple to fix the bug and support Displayport 1.2 MST like they advertise they support?

Or is asking them to be truthful in their advertisements too much?

Ah well if thats the case then it seems Apple doesnt support DisplayPort, since MST is a non-optional component of the spec, and has been for the last 4 revisions. Hopefully they can fix their broken DisplayPort implementation.