[PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinxuart 16550.

[Stephen Neuendorffer]

The device tree generator now reflects this.

Steve

> -----Original Message-----
> From: linuxppc-dev-bounces+stephen.neuendorffer=xilinx.com at ozlabs.org [mailto:linuxppc-dev-
> bounces+stephen.neuendorffer=xilinx.com at ozlabs.org] On Behalf Of Arnd Bergmann
> Sent: Wednesday, April 02, 2008 9:16 PM
> To: linuxppc-dev at ozlabs.org
> Cc: John Linn
> Subject: Re: [PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinxuart 16550.
> 
> On Thursday 03 April 2008, Grant Likely wrote:
> > >
> > >  Since it is not really compatible with ns16550, shouldn't you at least specify
> > >  a different "compatible" property? That way, the driver won't do incorrect
> > >  accesses when you try to use an old driver with a device tree that specifies
> > >  one of these.
> >
> > Heh; we've gone back and forth on this issue.  The problem is that we
> > have a common case of ns16550 like devices that require a little bit
> > of register address tweaking that spans a whole range of vendors (so
> > adding a compatible match with each of those vendor's prefixes is
> > probably non-scalable).  So, if "ns16550" is not a good idea, then
> > what should be used?  "sparse16550" has been suggested more than once.
> 
> After another IRC discussion between Grant, Segher and myself, we concluded
> that we don't need to invent a new "compatible" value, as only new device
> trees with old kernels will have a problem with this, and they don't work
> in the first place.
> 
> The devices will still have their specific "compatible" value, e.g.
> "xlnx,plb-uart16550-1.00.c", followed by "ns16550", and possibly
> "ns16450" and "i8250", although the last two do not have an effect
> on Linux.
> 
> Josh, can you please forward all three patches in their latest version?
> 
> Acked-by: Arnd Bergmann <arnd at arndb.de>
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