[PATCH 1/4] ARM: sa1100: fix sa1100 after sparse irq conversion

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Sun, Feb 19, 2012 at 09:21:19AM -0600, Rob Herring wrote:
> On 02/18/2012 05:18 PM, Russell King - ARM Linux wrote:
> > On Thu, Feb 16, 2012 at 09:32:11PM -0600, Rob Herring wrote:
> >> From: Rob Herring <rob.herring@calxeda.com>
> >>
> >> SA1100 was converted to sparse irq in parallel with include of mach/irqs.h
> >> being removed from asm/irq.h when sparse irq is enabled, resulting in lots
> >> of compile errors.
> > 
> > Can this be applied before the change to enable sparse IRQ for sa11x0
> > platforms without breaking them?
> 
> All but the rename of NR_IRQS to SA1100_NR_IRQS should be fine, but I
> can change it to leave NR_IRQS.

This isn't going to work.

If we update stuff to include mach/irqs.h, then we end up with mach/irqs.h
trying to override NR_IRQS in asm/irq.h:

#ifndef CONFIG_SPARSE_IRQ
#include <mach/irqs.h>
#else
#define NR_IRQS NR_IRQS_LEGACY
#endif

which spits out a lovely warning:

In file included from arch/arm/mach-sa1100/irq.c:20:
arch/arm/mach-sa1100/include/mach/irqs.h:86:1: warning: "NR_IRQS" redefined
In file included from arch/arm/include/asm/hardirq.h:6,
                 from include/linux/hardirq.h:7,
                 from include/linux/interrupt.h:12,
                 from arch/arm/mach-sa1100/irq.c:14:
arch/arm/include/asm/irq.h:9:1: warning: this is the location of the previous definition

There's three solutions I can think to this:

1. you need to decouple the SPARSE IRQ conversion from the removal of
   mach/irqs.h, so that there's a clean way to transition
2. I rebase the 100 odd otherwise unrelated sa11x0 patches on top of your
   stuff, which isn't going to be a nice experience.
3. I drop the final commit for this merge window to convert sa11x0 to
   sparse IRQ and the sparse IRQ conversion patch becomes quite large
   (basically meaning that all the includes have to be changed in unison
   with enabling sparse IRQ.)

(1) I think is the right solution, because it means that there's a nice
easy transition path for everyone in the future without requiring (3)
to happen every time.