Does lede suport external phy via rgmii2 for MT7621 platform

I have a mt7621 based board, it's six ethernet port, the 6th port is ar8035 phy. I have build latest 17.01 lede, but seems the ethernet doesn't work. How do i config the dts file and resolve the problem?

Most likely it is connected via PCI,check with lspci and then specify it in DTS if it is connected

Seems not, it is rgmii2 interface of mt7621.

Then this thread could help you

Thanks a lot!
Right, mt7620 is support external phy via rgmii, it is use port4. But mt7621 should be used port5 to connect the external phy. From the source code of gsw_mt7621.c, in function mt7621_gsw_probe(), it is not correct.
of_property_read_string(np, "mediatek,port4", &port4);
if (port4 && !strcmp(port4, "ephy"))
gsw->port4 = PORT4_EPHY;
else if (port4 && !strcmp(port4, "gmac"))
gsw->port4 = PORT4_EXT;
gsw->port4 = PORT4_EPHY;

And comparing soc_mt7620.c and soc_mt7621.c, there is no mt7620_port_init() function, so even if configuring it in dts file, it still does not work.
Is above correct?