Pro Display XDR as USB-C Dock?

[adamwathan]

Anyone who has received their Pro Display XDR yet been able to test what you're able to connect to the three USB-C ports while powering everything through only a single cable from your MacBook Pro/Mac Pro?

In my case I've got a small USB audio interface (Focusrite Scarlett 2i4), and Elgato Cam Link for using my Sony a6000 as a webcam, and a little Anker USB-A hub for connecting my wired keyboard/mouse and charging my phone.

No idea how much I can push over that single Thunderbolt connection to the monitor, worried the 6K of image signal isn't going to leave room for anything serious like the audio interface or Cam Link.

Am I gonna be able to keep that stuff plugged in to the monitor (with the right adapters) or do I need to connect a hub like the Caldigit TS3 directly to my 16" MacBook Pro using another port for everything to work?

If I do have to use two ports on the MacBook, can I use two ports on the same side, or should the Pro Display XDR go into a port on the left, and the TS3 into a port on the right (I've heard you only get full speed/bandwidth out of one port per side?)

 

[simonnelli]

AFAIK the ports negotiate USB3 maximum with DSC capable graphics cards (MBP 16" and most probably the now yet available W5700X), connecting the Pro Display to any other MPX graphics card leads to USB2 speeds because the rest of the bandwidth is needed for the display.

I think you'd be better of using a real USB-C or thunderbolt hub if you can't or won't connect your peripherals directly to the Macbook/Mac Pro.

See my other post: https://forums.macrumors.com/threads/the-pro-display-xdr-buyers-thread.2216359/post-28090145

 

[joevt]

What does the following command report?

system_profiler SPUSBDataType

If the display is running at 6K, the tech specs say the USB performance is reduced to USB 2.0. The command will tell us if the USB devices are connected using USB 2.0 or USB 3.x. It's the same information shown in System Information.app. USB 3.x could be "Up to 5 Gb/s" or "10 Gb/s" (but the specs suggest the XDR has a USB 3.0 hub limited to 5 Gbps). But if there's not enough PCIe bandwidth, than a USB 3.0 hub could be limited to much less than 5 Gb/s.

Do USB audio interfaces and webcams require more than USB 2.0 speed?
The Focusrite Scarlett 2i4 is a USB 2.0 device so it should be ok.
The Elgato Cam Link is a USB 3.0 device. It might not work.

Connecting the devices on the opposite side of the XDR is safest but I don't know if it's required. I'm not sure if the 6K DisplayPort to Thunderbolt conversion process (for the XDR) affects the USB bandwidth of the other Thunderbolt port of the same side Thunderbolt controller.

I know that connecting two fast Thunderbolt drives (22 Gbps) to the same controller does not work well (both use PCIe to Thunderbolt conversion - raiding both ports together only gives about 23 Gbps - only slightly more than the 22 Gbps of a single port - much less than the expected 32 Gbps of the controller).

It might be handy to have a fast external USB (950 MB/s) or Thunderbolt (2750 MB/s) drive to measure bandwidth differences of the USB-C ports of the MacBook Pro and XDR display. A USB-C to NVMe or Thunderbolt to NVMe adapter work well for this.

 

[ChromeCrescendo]

Hmmmm...so basically the USB-C ports on the XDR are only good for charging or synching an iPhone?

 

[joevt]

Hmmmm...so basically the USB-C ports on the XDR are only good for charging or synching an iPhone?

They can do USB 2.0 if connected with USB-C or if connected by Thunderbolt to a GPU that supports DisplayPort 1.4 but does not support DSC.

They can do USB 3.0 if connected by Thunderbolt to a GPU that supports DisplayPort 1.4 and DSC.

So keyboard, mouse should always be ok. Flash drive maybe (the usual slower kind). Faster drives will work but I wouldn't use them for work that requires many files (software development) or large files (photo/movie editing).

 

[ChromeCrescendo]

They can do USB 2.0 if connected with USB-C or if connected by Thunderbolt to a GPU that supports DisplayPort 1.4 but does not support DSC.

They can do USB 3.0 if connected by Thunderbolt to a GPU that supports DisplayPort 1.4 and DSC.

So keyboard, mouse should always be ok. Flash drive maybe (the usual slower kind). Faster drives will work but I wouldn't use them for work that requires many files (software development) or large files (photo/movie editing).

I think the USB-C ports on the XDR are downstream only - for charging and syncing

I do not believe I could connect my camera to the XDR to upload photos to the computer

Am I right?

 

[joevt]

I think the USB-C ports on the XDR are downstream only - for charging and syncing

I do not believe I could connect my camera to the XDR to upload photos to the computer

Am I right?

My answer was unclear. I will try again:

The downstream USB-C ports of the XDR can be used like a USB hub to connect USB devices that will transmit data to the computer or receive data from the computer.

The maximum speed of the USB data transfer depends on how the XDR is connected to the computer (USB-C or Thunderbolt) and, in the case of Thunderbolt, what kind of signal the GPU sends (HBR2 with DSC or dual HBR3).

The downstream USB-C ports of the XDR can do USB 2.0 if the XDR is connected upstream with USB-C, or if the XDR is connected upstream with Thunderbolt to a GPU that supports DisplayPort 1.4 but does not support DSC.

The downstream USB-C ports of the XDR can do USB 3.0 if the XDR is connected upstream by Thunderbolt to a GPU that supports DisplayPort 1.4 and DSC (such as the W5700X).

 

[Adult80HD]

I think the USB-C ports on the XDR are downstream only - for charging and syncing

I do not believe I could connect my camera to the XDR to upload photos to the computer

Am I right?

In short, no, you are wrong. If you are connecting the XDR to a 16" MBP or to a Mac Pro 7,1 with the W5700X MPX module you'll be able to connect any device to the XDR and get full TB3/USB 3.0 functionality. With any other connection, you get just TB with USB 2.0 speeds.

I actually have connected my Sony A7R IV to one of my XDR displays to remote control it, and it works like a charm. See attached photo and you'll see the cable running from the camera to the XDR.

 

[Nütztjanix]

Just out of curiosity - what is that we're looking at? Seems to be some kind of crystal?

 

[ChromeCrescendo]

In short, no, you are wrong. If you are connecting the XDR to a 16" MBP or to a Mac Pro 7,1 with the W5700X MPX module you'll be able to connect any device to the XDR and get full TB3/USB 3.0 functionality. With any other connection, you get just TB with USB 2.0 speeds.

I actually have connected my Sony A7R IV to one of my XDR displays to remote control it, and it works like a charm. See attached photo and you'll see the cable running from the camera to the XDR.View attachment 910433

I am glad I am wrong - I was merely going by what Apple states that the XDR's USB-C ports are for charging and syncing - if you are stating that in the real world, you can upload photos from your Sony to your Mac via the XDR then that has brought a smile to my face

 

[Adult80HD]

Just out of curiosity - what is that we're looking at? Seems to be some kind of crystal?

Sure, on the screen you are seeing tiny crystal inclusions (rutile) in a ruby. I built the setup you see using a precision macro rail, some tubes and tube lens and a high-resolution Mitutoyo microscope objective. It allows me to created stacked images at high resolution.
[automerge]1588172863[/automerge]

I am glad I am wrong - I was merely going by what Apple states that the XDR's USB-C ports are for charging and syncing - if you are stating that in the real world, you can upload photos from your Sony to your Mac via the XDR then that has brought a smile to my face

Yeah, the word "syncing" is an odd choice and I'm guessing in their mind they are thinking it's a great term that covers both uploading and downloading. I've also connected hard drives to the ports on the back of the XDRs. Since I have Radeon Pro Vega II cards in my MP, I only get USB 2.0 speeds, but that's not a big deal.

 

[ChromeCrescendo]

I waited to get the W5700x because I recall reading that it would allow the USB-C ports on the XDR display to run at USB3 rather than USB2

However, in system information it shows it is only running at 480mbps rather than 5Gbps

So, am I correct in thinking whatever I read previously re: USB speeds when connecting the XDR to the W5700x were incorrect?

 

[joevt]

I waited to get the W5700x because I recall reading that it would allow the USB-C ports on the XDR display to run at USB3 rather than USB2

However, in system information it shows it is only running at 480mbps rather than 5Gbps

So, am I correct in thinking whatever I read previously re: USB speeds when connecting the XDR to the W5700x were incorrect?

Provide the output of the following so we can see what's going on:

{
/System/Library/Extensions/AppleGraphicsControl.kext/Contents/MacOS/AGDCDiagnose -a | grep -E 'BR|DSC|Pixel|Bit|Color|Range|Link|Lane'
ioreg -w0 -irtk locationID
system_profiler SPHardwareDataType SPThunderboltDataType SPUSBDataType SPPCIDataType SPDisplaysDataType | sed '/Serial Number/d;/UUID/d'
} > XDR_Usb_Thunderbolt_PCI_Info.txt 2>&1
open .

Read more at #130

 

[ajm057]

I am running a 2019 16" MBP with Radeon Pro 5600M GPU. The macOS is 11.0.1 Big Sur. The MBP has 2.4Ghz 8-core Intel i9 chip, 64 GB RAM and 8TB SSD.

It is attached to 2 XDR displays, and 2 RAIDS, one of which that also serves as a NAS has a CalDigit Hub attached via a T3 port. There are other devices daisy chained to the XDR (Logi 4k camera and iPad Pro) and the CalDigit (xrite screen calib).

I have attempted to plug additional HDDs daisy chained to either the XDR or the CalD - but no joy yet. I also tried connecting a DAC via USB connected to the XDR with an AudioQuest DragonTail Carbon USB A to C Adapter no joy yet.

I ran your script and attached a copy of the output file.

Please let me know how you get on

 

[joevt]

I am running a 2019 16" MBP with Radeon Pro 5600M GPU. The macOS is 11.0.1 Big Sur. The MBP has 2.4Ghz 8-core Intel i9 chip, 64 GB RAM and 8TB SSD.

It is attached to 2 XDR displays, and 2 RAIDS, one of which that also serves as a NAS has a CalDigit Hub attached via a T3 port. There are other devices daisy chained to the XDR (Logi 4k camera and iPad Pro) and the CalDigit (xrite screen calib).

I have attempted to plug additional HDDs daisy chained to either the XDR or the CalD - but no joy yet. I also tried connecting a DAC via USB connected to the XDR with an AudioQuest DragonTail Carbon USB A to C Adapter no joy yet.

I ran your script and attached a copy of the output file.

Please let me know how you get on

Please reattach as zip

 

[swrobel]

I'm trying to figure out why I can't daisy chain a 22" LG Ultrafine 4K display to my Pro Display from my MBP 16". The 22" (22MD4KA) is a USB-C display, unlike all of the other Ultrafines, so it should work in theory, right? However, when I connect it & look at system information, it shows the LG being on the USB 2.0 bus of the Pro Display. I verified that I'm able to drive other USB 3.1 devices via the Pro Display's hub by connecting a Belkin gigabit ethernet adapter.

 

[Nütztjanix]

I'd say it's a bandwidth issue. Does the 16" MBP support DP2.0?

 

[joevt]

I'm trying to figure out why I can't daisy chain a 22" LG Ultrafine 4K display to my Pro Display from my MBP 16". The 22" (22MD4KA) is a USB-C display, unlike all of the other Ultrafines, so it should work in theory, right? However, when I connect it & look at system information, it shows the LG being on the USB 2.0 bus of the Pro Display. I verified that I'm able to drive other USB 3.1 devices via the Pro Display's hub by connecting a Belkin gigabit ethernet adapter.

None of the USB-C ports of the XDR support USB-C DisplayPort Alt Mode. That's because both DisplayPort outputs of the Thunderbolt controller in the XDR are connected to the XDR's display controller in case you connect the XDR to a GPU that does not support DSC (in that case, one DisplayPort output is used for the left half of the display and the other DisplayPort output is used for the right half of the display). One of the DisplayPort outputs is from the downstream Thunderbolt port of the Thunderbolt controller, that's why the XDR does not have a downstream Thunderbolt port.

If you want to connect a display to the XDR, then it needs to be something like DisplayLink which does not use DisplayPort input - it takes compressed video using USB and then outputs it as DisplayPort.

 

[joevt]

I'd say it's a bandwidth issue. Does the 16" MBP support DP2.0?

Nothing supports DisplayPort 2.0. Maybe you mean DisplayPort 1.4? The 16" MBP supports DisplayPort 1.4 with DSC, so it can connect to the XDR display using a single four lane HBR2 connection with DSC leaving plenty of bandwidth for USB 3.x devices or other Thunderbolt devices.

 

[Nütztjanix]

Nothing supports DisplayPort 2.0. Maybe you mean DisplayPort 1.4? The 16" MBP supports DisplayPort 1.4 with DSC, so it can connect to the XDR display using a single four lane HBR2 connection with DSC leaving plenty of bandwidth for USB 3.x devices or other Thunderbolt devices.

You‘re correct. I meant DP 1.4. But you already explained why it won’t work. 🙂

 

[swrobel]

None of the USB-C ports of the XDR support USB-C DisplayPort Alt Mode. That's because both DisplayPort outputs of the Thunderbolt controller in the XDR are connected to the XDR's display controller in case you connect the XDR to a GPU that does not support DSC (in that case, one DisplayPort output is used for the left half of the display and the other DisplayPort output is used for the right half of the display). One of the DisplayPort outputs is from the downstream Thunderbolt port of the Thunderbolt controller, that's why the XDR does not have a downstream Thunderbolt port.

If you want to connect a display to the XDR, then it needs to be something like DisplayLink which does not use DisplayPort input - it takes compressed video using USB and then outputs it as DisplayPort.

Thank you so much for the detailed explanation! I guess 2 cables to my MBP it is...

 

[joevt]

Thank you so much for the detailed explanation! I guess 2 cables to my MBP it is...

I suppose you could connect both displays to a OWC Thunderbolt 4 Hub or Dock. I think it should work because the MacBook Pro 16" has 5300M or 5500M or 5600M graphics which should use DSC to connect the XDR, leaving enough bandwidth for the 4K display. You can check for DSC using the AGDCDiagnose command.

 

[swrobel]

I suppose you could connect both displays to a OWC Thunderbolt 4 Hub or Dock. I think it should work because the MacBook Pro 16" has 5300M or 5500M or 5600M graphics which should use DSC to connect the XDR, leaving enough bandwidth for the 4K display. You can check for DSC using the AGDCDiagnose command.

Think that would work despite their site saying "Up to dual 4K displays or a 5K/6K/8K display"

 

[joevt]

Think that would work despite their site saying "Up to dual 4K displays or a 5K/6K/8K display"

I think it should work. dual 6K if they are using DSC.

 

[swrobel]

I think it should work. dual 6K if they are using DSC.

I finally got my hands on this dock after a lengthy preorder wait. Unfortunately it seems it's only supported in macOS 11.1 & above, but I've stayed on Catalina because I saw you post that Big Sur broke DSC. Any advice for what to do now? 🤔

Edit: I've tried booting with it connected as you've suggested in previous posts but only USB devices are detected, not Thunderbolt.