Re: [PATCH 5/5] ARM: vexpress: DT-based support for CoreTiles Express A5x2 and A9x4

[Pawel Moll <pawel.moll@arm.com>]

On Wed, 2011-11-16 at 15:36 +0000, Dave Martin wrote:
> > +/include/ "skeleton.dtsi"
> > +
> > +/ {
> > +	model = "V2P-CA5s";
> > +	arm,hbi = <0x225>;
> 
> Are these part numbers formally hex numbers?  Is so, fine.  Otherwise
> maybe it would me safer to make properties of this kind strings.

Hex values. See
http://infocenter.arm.com/help/topic/com.arm.doc.dui0447e/CACBEHGJ.html

> > +config ARCH_VEXPRESS_V2P_CA5S_CA9
> > +	bool "DT: CoreTiles Express A5x2 and A9x4"
> 
> This "DT" stuff is a bit cryptic -- also it's an implementation feature
> rather than part of the core nature of this config option.

Yeah, I know. I just didn't feel very verbose doing the Kconfig changes.

> Also, pedaitically, the product name is "CoreTile Express".

Ha ha - I wanted to express the plurality of A5 _and_ a9 ;-) Never mind,
will change it.

> Finally, this option does not support those core tiles, as such; rather
> it supports particular whole-platform configurations involving those
> core tiles.
> 
> How about "CoreTile Express A5x2 and A9x4 based platform support"

Fine with me - I'll use your wording :-)

> > +	select ARCH_VEXPRESS_RS1
> > +	select ARCH_VEXPRESS_DT
> > +	select ARM_ERRATA_720789
> > +	select ARM_ERRATA_751472
> > +	select ARM_ERRATA_753970
> > +	help
> > +	  This option enabled Device Tree based support for
> > +	  CoreTile Express A5x2 (V2P-CA5s) and
> > +	  CoreTile Express A9x4 (V2P-CA9).
> > +
> > +	  Note that you must provide kernel with a valid DTB
> > +	  for the board if you want to use this option.
> 
> For the above reasons, the following alternative text might be a bit
> more user-friendly:
> 
> 	help
> 	  This option enables support for systems using any of the the following
> 	  ARM core tiles on the Versatile Express motherboard:
> 
> 	      CoreTile Express A5x2 (V2P-CA5s)
> 	      CoreTile Express A9x4 (V2P-CA9)
> 
> 	  You must boot using a Flattened Device Tree in order to use these
> 	  platforms.  The traditional (ATAGs) boot method is not usable on
> 	  these boards with this option.
> 
> 	  If you want your kernel to run on one of these platforms and your
> 	  bootloader supports Flattened Device Tree based booting, say Y.

Same here - will copy this :-)

> Do we still support the "old style" V2P-CA9x4 support?  If so, we could
> add a comment explaining that is available as an alternative, for now.

We do, with the non-DT option (Russell wouldn't be very happy if his
serial port multiplexer stopped working ;-)

> >  endmenu
> > diff --git a/arch/arm/mach-vexpress/Makefile b/arch/arm/mach-vexpress/Makefile
> > index 90551b9..06e3687 100644
> > --- a/arch/arm/mach-vexpress/Makefile
> > +++ b/arch/arm/mach-vexpress/Makefile
> > @@ -4,5 +4,6 @@
> >  
> >  obj-y					:= v2m.o
> >  obj-$(CONFIG_ARCH_VEXPRESS_CA9X4)	+= ct-ca9x4.o
> > +obj-$(CONFIG_ARCH_VEXPRESS_V2P_CA5S_CA9) += v2p-ca5s_ca9.o
> >  obj-$(CONFIG_SMP)			+= platsmp.o
> >  obj-$(CONFIG_HOTPLUG_CPU)		+= hotplug.o
> > diff --git a/arch/arm/mach-vexpress/v2p-ca5s_ca9.c b/arch/arm/mach-vexpress/v2p-ca5s_ca9.c
> 
> [...]
> 
> > +DT_MACHINE_START(VEXPRESS_V2P_CA5S_CA9, "ARM Versatile Express")
> 
> We could try to name the platform fully here, but these strings would
> get very long -- so I agree it best to leave that to be specified in
> the device tree.

Having such machine name here and model in the dts gives such a nice
message in the log:

Machine: ARM Versatile Express, model: V2P-CA9

Which is sort-of-correct.

Cheers!

Paweł



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