MacBook Pro Early 2015 with Dell DisplayPort 1.2 / MST monitor.

Question

MacBook Pro Early 2015 with Dell DisplayPort 1.2 / MST monitor.

I am trying to use a Early 2015 MacBook Pro with a Dell U2715H monitor in DP1.2 mode so I can use the MST support in my new MacBook to daisy chain 2 of these screens together. However it doesn't work. Daisy chaining without DP1.2 enabled results in the displays being mirrored and only 1 display being detected by the laptop. Enabling DP1.2 on the screen connected to the laptop causes the screen to go blank and it for it to detect no signal. Even without they daisy chained. The first monitor is always detected by the laptop but in no configuration does the 2nd one ever show up.

This feature seems to be advertised as working both on the monitor and on the laptop but I am not having much luck with it 😟 Is the laptop buggy? Is the monitor? Is it both of them?

MacBook Pro with Retina display, OS X Yosemite (10.10.3)

Posted on Apr 13, 2015 4:27 AM

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Answer 1

Brentx

Level 1

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Apr 13, 2015 11:55 AM in response to alexstapleton

I have the same setup as you, only with a late 2013 MBP. I experience the same problem as you. From what I've been able to gather, OS X does not support Display Port 1.2 MST. Even though this works with Apple's own displays, and now that it works with the new Dell 5K displays in 10.10.3, Apple has not enabled this functionality for daisy chaining two displays together.

It is a little angering, as Apple's devices are DP 1.2 compatible, but they purposely disable this feature. I am not sure what their reasoning is for this.

All we can do is hope they enable this in a future update, as I think it is a software limitation.

In the mean time, I have been running one U2715H on DisplayPort, and another on HDMI, as this leaves and additional thunderbolt port available for the ethernet adapter.

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Answer 2

Apr 15, 2015 2:06 AM in response to Brentx

I assume you are trying it with a 15" MBP? Mines a 13" 2015 version which is the only 13" advertised to support MST on this page Using 4K displays and Ultra HD TVs with your Mac - Apple SupportIt definitely seems like a software limitation since the hardware definitely has DP1.2 and MST support now.

This thread seems to be about the same problem Daisy chain two display port monitors (Dell U2913WM) to new Mac mini Thunderbolt? No comment from Apple about what's going on here either.

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