On 28/05/12 17:03, Russell King - ARM Linux wrote:

quoted

Initially, with my RFC patch, there was an #ifdef for bigger FIFO in
case of LPC32xx where we have a 16550A variant with 64 byte fifos.

What are all the differences?  Is it just a larger FIFO?

Yes, this is how it's summarized in the manual (LPC32xx SoC).

quoted

So maybe 16750 is the better choice for me, anyway. Already supported in
of-serial. Works for now, but need more testing. Another hint is that
16750 is advertised as "IP core for Soc" which matches the case of LPC32xx.

16750 also has automatic hardware flow control support, selectable through
bit 5 in the MCR register.  If your UART has that, then it's probably a
16750 derivative rather than a 16550 or 16650 derivative.

16650s have an EFR register at offset 2, selectable by writing 0xBF into
the LCR register, which the 16750 doesn't have.  16650 also has automatic
hardware flow control, bit this is selected through a couple of bits in
the EFR.

The 4 LPC32xx's "Standard" UARTs have neither of those.

Is it ok to use "ns16650", i.e. PORT_16650, or do I need to introduce a
FIFO depth configuration?

Thanks in advance,

Roland