That's not quite what I described. With my design either port can source or sink power, they just do it on opposite pins. And it wouldn't be USB-A vs USB-B, but

That's not quite what I described. With my design either port can source or sink power, they just do it on opposite pins. And it wouldn't be USB-A vs USB-B, but male vs female So for USB, you would need a 5-pin port, where two are devoted to power. And both USB-A and USB-B would have the same wiring, but male ports source and supply on opposite pins as the female ones. Then M-M or F-F cables crossover the power lines.