On Mon, May 28, 2012 at 06:27:20PM +0200, Roland Stigge wrote: > On 28/05/12 17:03, Russell King - ARM Linux wrote: > >> 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). > > >> 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? I think you need a new type, because as I said above, 16650s have that additional EFR, and we will attempt to access that register which isn't present in yours. It's not solely about fifo depth. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
