DisplayPort 1.2 Monitor Daisy Chaining - Works in BootCamp but not on Mac

Question

DisplayPort 1.2 Monitor Daisy Chaining - Works in BootCamp but not on Mac

Hi,

I have an Early 2011 Macbook Pro with the following setup:

The Macbook is connected to one Dell monitor using DP 1.2 from the DisplayPort
The first monitor is then daisy chained to a second, also using DP 1.2
There are three screens total, and the setup is like Mac -> Screen 1 -> Screen 2 (all using DP 1.2)

Here is my problem. I cannot get a 3-way split desktop where each desktop is separate while running Mac.

I have installed Windows 8.1 in BootCamp and I can run all three monitors separately just fine. There are no issues at all.

The same cannot be said for when I boot into OSX. Clearly it's not a hardware issue if Windows supports it.

How can I have my Mac support this? I realize that I may have to hack into some settings and that's fine, just point me where to go.

Thanks.

Mac Pro, OS X Yosemite (10.10.2), Running Windows 8.1 in BootCamp

Posted on Feb 25, 2015 2:03 PM

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Answer 1

Loner T

Level 9

59,536 points

Feb 25, 2015 6:28 PM in response to JeremiahBenes

1. How many monitors show up in System Preferences -> Displays on the OS X side?

2. Can you check About This Mac -> System Report -> Graphics/Displays. This should be the same as what is shown in 1.

3. What happens if you turn off Screen 2 and turn it back on in OS X? Does the output in 1 and 2 change?

4. With Screen 2 powered on, if Screen 1 is turned off, does Screen 2 output video? Check the status in 1 and 2.

5. After Step 4, if Screen 1 is turned back on, do both Screen 1 and Screen 2 output video? Check the status in 1 and 2.

6. What is the Dell Monitor model?

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Answer 2

Mar 23, 2015 9:52 AM in response to Loner T

Only one monitor shows up on the OSX side.
System Report shows two graphics items, one via PCIe and one built-in. The AMD Radeon graphics card is showing two monitors connected (confirming what was found in step 1)
Turning off the second screen makes no changes to what was found in 1 and 2.
When Screen 1 is powered off, Screen 2 does not output anything and is not recognized in System Preferences and System Report.
When Screen 1 is turned back on, one monitor is found like in Steps 1 and 2. Both display black screens but indicate they are receiving some kind of signal.
The monitors are both Dell U2415.

Here's the info that System Report shows about the monitor (the one that is recognized):

DELL U2415:

Resolution: 1920 x 1200 @ 59 Hz

Pixel Depth: 32-Bit Color (ARGB8888)

Display Serial Number: PVJVW49E24KL

Mirror: Off

Online: Yes

Rotation: Supported

Connection Type: DisplayPort

Adapter Firmware Version: 0.00

Television: Yes

Thanks for your help! I boot into Windows fairly frequently and I can confirm that everything still works on the Windows side.

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Answer 3

Loner T

Level 9

59,536 points

Mar 23, 2015 10:54 AM in response to JeremiahBenes

From MacBook Pro (15-inch, Early 2011) - Technical Specifications

Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on an external display, both at millions of colors

It may be a limitation of the OSX Display driver, even though the hardware supports as Windows shows.

Is it possible for you test the following topology - Mac -> DP Display 1 -> TB Storage -> DP Display 2 or variants and see if any of these work.

You may also want to check Apple Mini DisplayPort adapters: Frequently asked questions (FAQ) - Apple Support and Thunderbolt ports and displays: Frequently asked questions (FAQ) - Apple Support.

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Answer 4

Mar 23, 2015 2:52 PM in response to Loner T

What do you mean by TB Storage?

Is there any way I can tweak the driver so that it will support two monitors? Or is there a ticket I can open up with Apple?

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Answer 5

Loner T

Level 9

59,536 points

Mar 23, 2015 3:12 PM in response to JeremiahBenes

TB = Thunderbolt storage.

Since you have a TB port, not a DisplayPort (as mentioned in the TechSpec link), the OSX driver, when it detects a storage using TB, it needs to pass all frames, which may help diagnose the OSX driver.

Apple ticket may not help.

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Answer 6

jquispel

Level 1

0 points

Jun 10, 2015 9:48 AM in response to Loner T

Any update guys? I try to do the same thing on a new mac pro late 2013. No luck with daisychain. It won't even put one screen on when the settings are enabled for monitor displayport 1.2 mode. With 1.1 mode (1.2 turned off) the screen is mirrored.

thanks,

jasper

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Answer 7

Loner T

Level 9

59,536 points

Jun 10, 2015 11:56 AM in response to jquispel

You are referring to a completely different Mac. The MacPro behaves completely differently.

Please see

Mac Pro (Late 2013): Using multiple displays - Apple Support

Mac Pro (Late 2013): Using multiple displays on Windows 8 via Boot Camp - Apple Support.

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