What is portmap and portdisable?

I need to disable a LAN port of my SKYLAB SKW92 board and I have to use these pins as GPIO or UART2 . I added below lines in the dtsi file and wan port and 1 lan port got disabled, I need to know what actulally its means ?

&esw {
	mediatek,portmap = <0x3d>;
	mediatek,portdisable = <0x29>;

and how to disable specific port that I want. and use them as other function like GPIO or UART.