Re: [PATCH] serial: Enable Freescale 16550 workaround on arm

[Arnd Bergmann <arnd@arndb.de>]

On Friday 02 October 2015 18:49:24 Scott Wood wrote:
> > Other than that, I wonder if we should do this completely differently
> > and have the respective entries in of_platform_serial_table[] with
> > an appropriate PORT_* constant to handle the freescale case.
> 
> I'd considered that, but it seemed like it would be more complicated, with no 
> real benefit.  We'd need to add a new PORT for the non-fifo64 case, and it 
> would need to otherwise behave like PORT_16550A.  There's no room for an 
> extra 8250-style PORT number unless we break PORT_MAX_8250 or renumber the 
> "ARM specific type numbers", and for some reason these PORT numbers are 
> defined in uapi (even if there's some legacy reason for that, do we really 
> need to keep adding to it?).  We'd also need to make sure that autoconfig() 
> doesn't overwrite the new PORT number (or ignore the fact that it gets 
> overwritten after using it to substitute handle_irq).  It would also increase 
> the discrepancy between how the same issue is handled on ARM versus PPC (with 
> the latter using arch/powerpc/kernel/legacy_serial.c which doesn't supply 
> PORT numbers).
> 
> The above check wouldn't go away, as it's not something currently addressed 
> by struct serial8250_config (unless you're also asking for a new flag for 
> that struct, in which case it would merely be moved elsewhere); it would just 
> require a bunch of changes elsewhere to support changing it from a simple 
> compatible check to a PORT check.

Ok, let's keep your version then, unless someone has a better idea.

FWIW, I think we should just move of_serial.c to drivers/tty/serial/8250/
now and remove the nwp specific bits.

Looking for a volunteer to actually do that work ;-)

	Arnd