It is not possible to control the FETs using VBUS_FET_EN through a HPI command from an EC. Could you please let us know when you would like to disable the BCR and provide power directly?
I would like to provide power directly before the usb cable is connected and the rest of the pcb is off. I also want to make sure it is safe and will not back drive the host when connected. In terms of the circuit to use VBUS_FET_EN, I was thinking of doing this...
Where J1 Is just a 2 pin jumper, which is open when I want to use usb power and closed when I want to power directly from external source.
Yes, this could work looking at the VGS(th) of your FET.
-You could use a power OR-ing method as well or a SPDT switch between the FETs and external power supply. This would take care of the back-powering in case the host is also connected.
-Could you please let us know how the BCR is powered?