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I am running ubuntu 13.10 on a desktop system and I have 2 monitors that I am trying to connect via Displayport's 1.2 multi-streaming support.

The system is equiped with an Intel Core i7-4770K processor and I'm using the displayport (1.2) output of the Intel HD Graphics 4600 to connect the computor to a Dell U2413 monitor. The second monitor (Dell U2412) is connected via a displayport 1.1 cable to the Dell U2413 monitor.

Ubuntu detects the U2413 monitor fine, but it doesn't detect the U2412 monitor. (The U2412 monitor is only recognised when I connect it directly to computor.) The daisy chain setup works fine under Windows 7 though ... Any ideas on how to get it working under ubuntu?

6

MST is not implemented in Linux at this time nor is it implemented in Apple's OSX despite the fact that the hardware has supported it for several years but Apple will have it implemented sometime this year because it is required by the new 4K monitors that use DisplayPort 1.2 and Linux support will probably come around that time. The only OS that currently properly supports MST is Windows because the drivers on that platform have it implemented. Also, the 2412 monitor uses DP 1.1 which does not support MST, so you should replace the monitor with another 2413.

  • 1
    Thanks for the clarification. One note though, I know that DP 1.1 doesn't support MST, but this doesn't prevent me from linking the 2412 to the 2413 via DP (on windows). The last link in the chain doesn't need to support DP 1.2 ;) – Pieter Jan 12 '14 at 14:55
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    The last monitor in the chain doesn't need to support DisplayPort 1.2 with MST (daisy chaining), btw. – Levi Morrison Sep 3 '15 at 16:02
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Good news everybody!

You don't have to manually build bleeding edge software any more. I have a Dell E7240 with Intel HD running dual monitors via dockstation right now.

You have to do either:

  • Upgrade Ubuntu to a more recent release. 14.10/15.04+ appears to be supporting MST for Intel graphics out of the box.

  • If you want to keep running the latest LTS 14.04 (Trusty), install a newer Linux kernel (3.17+) or the backports from Utopic (14.10) through the Hardware Enablement channel provided for LTS release some time after newer stable releases have happened. Several other ways exist too. For manual Xorg updates PPAs like the xorg-edgers PPA will probably work too.

  • For me just updating to the 3.17 kernel using the linked deb got this fixed. Thank you! – Kenneth Wilke Feb 27 '15 at 20:35
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    Looks like Ubuntu 14.10 has proper video drivers out of the box. I've had 14.04 and have had to update drivers. – konstantin.zaikin Mar 3 '15 at 6:51
  • Can you elaborate on your laptop's video output and the external device you used? – iMoses Mar 9 '15 at 18:55
  • Hey. English is not my native language and I don't quite get what you want me to do. I have a Dell E7240 and a classic Dell dockstation with double Dell monitors attached via DVI cables to a dockstation. – konstantin.zaikin Mar 10 '15 at 9:26
  • These days I would say that this answer is the correct one, since it actually helps up the situation, concerning dual monitors and docking station and in my case Dell E5550, and the patch is within a stable kernel. – Learning Mar 23 '15 at 10:26
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David Airlie implemented MST support in the kernel and the xserver-xorg-video-intel driver.

To get it working on Ubuntu 14.04, you have to compile the linux kernel with his patch, as well as compile the intel X.org driver from git master.

With that, I got it working. My Thinkpad T440p's UltraDock has a display connected on DVI, one on DisplayPort and the laptop's own display running all at once:

enter image description here

The GitKernelBuild wiki page was helpful.

Detailled build instructions can be found in my blog post.

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    please see my answer. Linux Kernel 3.17 is stable now with all necessary bits and Intel drivers are available too. – konstantin.zaikin Nov 21 '14 at 5:51
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I've got a T540p notebook with docking station and Linux Mint 17 based on 14.04 LTS with 3.19 kernel and latest intel drivers together with an Asus 4k display which supports a resolution up to 3840x2160.

If the display is connected directly with the notebook via the mini DisplayPort connector all is working fine.

If the display is connected with the docking stations DisplayPort it is only detected with a max resolution up to 2560 x 1440. If 3840x2160 is selected the external display is not detected.

The Asus display needs two lanes for 4k support. The docking station also use several DP lanes to support the decoupling of DisplayPort and HDMI connections. Looks from a technically point of view like a DP hub (asus display) is connected with another DP hub (dock).

It seems to be that this special constellations (DP hub connected with another dp hub) currently aren't supported by the recent changes of the kernel and intel drivers.

  • You wrote: "It seems to be that this special constellations (DP hub connected with another dp hub) currently aren't supported by the recent changes of the kernel and intel drivers." -- Can you substantiate yr last assertion with references or links or the output of commands to reveal this lack of support ? Please complete yr answer or use paste.ubuntu.com to post link to output in yr answer - Danke. – Cbhihe Oct 13 '15 at 6:54

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