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DisplayPort 1.2 MST

Posted: Tue Jan 16, 2018 4:28 pm
by hwmartin
According to the specification for Intel Apollo Lake, the Atom/Celeron in the fitlet2 supports DisplayPort 1.2 and should therefore support DisplayPort MST.

I have two 4K displays with MST support. Using my Dell E7250 (5th gen Core i5) I am able to use DisplayPort MST and have both monitors daisy chained while running at 3840x2160@30Hz.

Unfortunately, when I try to do this in Xubuntu 17.10 on the fitlet2, I am getting the following error:
"xrandr: Configure crtc 0 failed"

The following combinations have been tested and work:
- 4K@30Hz (HDMI) + 4K@60Hz (DP; MST disabled)
- 1080p@30Hz + 1080p@30Hz (DP; MST enabled)
- 1080p@30Hz + 4K@30Hz (DP; MST enabled)

Unfortunately trying to output 4K to both monitors using DP MST on the fitlet2 fails.

1. Has CompuLab tested DisplayPort MST?
2. Can you confirm whether dual 4K output via DP MST is functional in Linux or another OS?

According to the specifications from Intel, this should be working.

Re: DisplayPort 1.2 MST

Posted: Sun Jan 21, 2018 1:58 pm
by tamir
Unfortunately Compulb haven't tested DisplayPort MST, hence we cannot confirm whether this should work at the moment.

Thank you.