A fairly common request, when you need to assemble a 2x2 video wall from available or non-specialized displays, now has a simple solution. Cypress CDPS-4KQ-AD Video Wall Controller!
1080p and 4K inputs as base, but not limited to.
Resulting wall resolution = 4x1080p!
HDCP 2.2 support, transparent work with EDID and remote control of the controller via network or RS232.