Displayport 1.2 MST/daisy chain - Dual Monitor setup - Intel graphics

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?

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.

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.

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:

The GitKernelBuild wiki page was helpful.

Detailled build instructions can be found in my blog post.

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.