For RGB, there is no initialization code to make this work out of the box, just pin configuration.
For MCU and RGB:
The IM[1:0] bits are used to set the MCU interface to either 16 or 18 bit (01 or 11). IM2 selects either Serial (0) or parallel (1) MCU interface. So for example, IM[2:0] = 011 would mean the MCU interface is running in 18-bit serial mode.
The RCM1 bit is used to select either the MCU (0) or RGB (1) interface modes (for writing display data to frame memory).
If the RGB interface mode is selected (RCM1 =... (More)