Maybe - but download the photo gallery for the "Henge" dock and look at the top and back views and compare those with pictures of the rMBP from the Apple website: you can clearly see where the dock connects to the rMBP. The three connections on the left would be 2xTB/DisplayPort and a USB3. The two on the
right would be a second USB3 port and... HDMI. Yet there's no HDMI on the dock.
So the dock could be using HDMI to get the third signal - which is what other demos of
three monitors on the rMBP have done.
Ohhh, I forgot about the HDMI port. Well that WOULD explain it then. Hmm. Still though, since it's DisplayPort 1.2 compatible, doesn't that mean it HAS to support all DP 1.2 features in order to use the standard? Maybe I'm grasping at straws but I'm really hoping that if DP hubs ever do come out, that they'll be compatible through my Mac's thunderbolt port.
Unfortunately, its been
widely reported that it doesn't - unless you chain another thunderbolt peripheral from the Thunderbolt display and chain the DisplayPort device from
that.
As I said - each TB controller extracts 1 display signal and one PCIe bus lane. The TB monitor uses the display signal to drive its screen - to get another display signal you need a second TB controller.
Ah, I recall reading that, that's right. The TB display sure is funky. For example, I've always understood that the video is carried by DisplayPort. I've always seen the diagrams showing something like this;
DisplayPort -->
Thunderbolt
PCI-Express -->
So, one thing I never understood, is why the TB display is not compatible with MiniDP? Even with reduced features. I would own one, except they aren't compatible with DisplayPort or anything BUT thunderbolt. I would be perfectly fine with losing all of the 'dock' features when plugging it in to my desktop PC's graphics card. Then I could use those features with my MBP when it's plugged into it. But I ordered the Cinema Display instead because of it's compatibility with my other machines. Simple cheap adapters will make it work with anything. In my mind, in order for thunderbolt to carry 'video', there'd basically have to be a GPU at the other end (in the display) which there's not.
iFixIt did a teardown and it seems like, from what I understand, the TB display does in fact use miniDP for video, but creates some sort of a 'handshake' with thunderbolt, and requires it (which we already know) to work. But, I just don't understand why Apple decided not to allow a 'legacy' mode where it could work as a Cinema Display?
I dunno. Still crossing my fingers for DP hubs that will work with a MBP, so I don't have to resort to a USB 'video adapter' for my other monitor.
Edit: Re-read it. Actually, the panel itself connects to the logic board via displayport. So it is, in fact, a DisplayPort monitor. But the thunderbolt logic board lacks the ability to 'pass through' displayport signals from a graphics card (like my 7970 in my desktop with miniDP). Too bad!