@Andreas_Wolf

I don't need 3D acceleration at this moment. The problem is I have Debian installed next to MorphOS and would like to get a 2k resolution on both systems. I have several graphics cards, but none of them work as expected.

E.g
Radeon HD3450 offers max FullHD (thru HDMI, there is no DP) on both systems.
Radeon HD 4650 also only FullHD (thru HDMI, DP gives black screen) and only on Morphos.
Radeon HD6450 gives 2k (thru DP) on Debian and black screen (thru HDMI and DP) on Morphos.

So I am asking if anyone is using Displayport on Morphos, Debian should handle it (I hope so).