Does anyone know yet if Thunderbolt 2 allows direct mini dp connection?

Discussion in 'Mac Pro' started by Zellio, Sep 16, 2013.

  1. Zellio macrumors 65816


    Feb 7, 2012
    Instead of the mini dp at the end of the chain?
  2. Mikey7c8 macrumors regular

    Sep 15, 2009
    Montreal, Canada
    Pretty sure the limitation was on the display, not the tb port
  3. zaphoyd macrumors regular

    Jun 25, 2002
    Based on my knowledge of the way Thunderbolt displays work Thunderbolt 2 will not change the mechanics of how DisplayPort is passed through except that the passed through DisplayPort signal will be a DP1.2 signal rather than 1.1.

    I would expect:
    - Mini DisplayPort monitor will still not be able to be connected directly to a Thunderbolt 2 monitor that is plugged into a Thunderbolt 2 port.
    - Mini DisplayPort monitor will continue to be able to be connected to the end of a Thunderbolt 2 chain where the last device is not a monitor (or some other device that uses a DisplayPort signal like some docks)
    - A 60Hz 4K display (and hopefully also an MST chain of smaller DisplayPort displays) will be able to be connected anywhere that Thunderbolt 1 would allow a DisplayPort monitor.
  4. deconstruct60 macrumors 604

    Mar 10, 2009
    If "direct connection" means plugging the mDP (mini DisplayPort ) device directly into a computer system's Thunderbolt (TB) ports, then yes. But it is not "yes" in the notion of 'instead of'. If there are no other TB devices, that is the end of the chain. A chain length of zero ( or 1 if count the starting device), but it definitely the end. Neither TB 1 or 2 have any problem with that.

    But DP1.2 can have multiple streams in it. So that is possible difference.

  5. zaphoyd macrumors regular

    Jun 25, 2002
    Sure. Directly plugging into the computer TB port puts it in DisplayPort passthrough mode where there isn't really a Thunderbolt chain at all. The main difference here with TB2 is that DisplayPort 1.2 passthrough is now supported. In theory the 2013 TB1 controllers should allow this as well, though Apple seems to have not used them in any of their 2013 macs so far. =(

    I hadn't thought of the ability to use DisplayPort MST on a Thunderbolt display to feed the signal back into the TB chain. Somehow I doubt anyone will actually do this.. Apple has no reason to want to allow you to buy anything other than more Apple Thunderbolt displays which wouldn't need such a feature. If they do though it would be much appreciated. If anyone other than Apple would make a TB display that would be awesome also.

    Yes, it is likely that a 60Hz 4k display at the end of a Thunderbolt chain would result in severely limited outgoing (from the computer) bandwidth for the rest of the Thunderbolt chain. I wonder how much the bandwidth limitations will affect any 4k Thunderbolt monitor that Apple might make. There wouldn't be much bandwidth left for the webcam/speakers/usb/firewire/ethernet ports on the existing ones much less for any devices in the chain after the display.

    I also wonder how TB2 flow control/QoS will work with respect to displays and audio devices now that the two channels are combined. Will a TB monitor on a TB2 chain with a fast SSD array have video or audio issues when the SSDs are being accessed at near TB2 line speeds? Does position in the chain imply priority? Something else?

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