It's a pefectly functional serial port when docked - a serial port doesn't need to have any control lines to still be a serial port, it just needs transmit, receive, and ground (which is missing unfortunately - see above!).

The port does have a hardware FIFO and we've had luck with 230k operation. IRQ latency on the ARM is generally better than that on PCs.

As with PCs and 16550 FIFOs, the flow control lines are software driven - you have to respond to IRQs and twiddle the flow control manually (by which point you could have emptied the fifo anyway). Hardware flow control on a PC with a 16550 is useless, really - all it can do is throttle the remote end if the software receive buffer is getting full.

UARTs with *actual* hardware flow control (eg, the 6850) are rare - the Startech 16650 does it though, as does the TI 16750 (though in a different way, just to be annoying).

Hugo