I have a Philips Brilliance 288P monitor, which should support 3840x2160@60hz.
My laptop has an Intel Graphics HD5500, which should also support this.
As I understand, with MST mode I should get two virtual monitors (DP1-1, DP1-2 or something),
instead of that all I'm getting is one DP1 device and I see this - Dropbox - 2015-04-13 12.04.04.jpg
I tried 3.19, 4.0-rc and 4.0-intel-drm-nightly kernels.
You can try any of the Linux support groups to see if there are any drivers available that will provide you with the functions you require.
See here for more information about Linux* support: