[ARM] 5295/1: make ZONE_DMA optional

Most ARM machines don't need a special "DMA" memory zone, and
when configured out, the kernel becomes a bit smaller:

|   text    data     bss     dec     hex filename
|3826182  102384  111700 4040266  3da64a vmlinux
|3823593  101616  111700 4036909  3d992d vmlinux.nodmazone

This is because the system now has only one zone total which effect is
to optimize away many conditionals in page allocation paths.

So let's configure this zone only on machines that need split zones.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -148,7 +148,6 @@ config ARCH_MAY_HAVE_PC_FDC
 
 config ZONE_DMA
 	bool
-	default y
 
 config GENERIC_ISA_DMA
 	bool
@@ -357,6 +356,7 @@ config ARCH_IXP4XX
 	select GENERIC_GPIO
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS
+	select ZONE_DMA if PCI
 	help
 	  Support for Intel's IXP4XX (XScale) family of processors.
 
@@ -503,6 +503,7 @@ config ARCH_SHARK
 	bool "Shark"
 	select ISA
 	select ISA_DMA
+	select ZONE_DMA
 	select PCI
 	help
 	  Support for the StrongARM based Digital DNARD machine, also known
@@ -524,6 +525,7 @@ config ARCH_DAVINCI
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_GPIO
 	select HAVE_CLK
+	select ZONE_DMA
 	help
 	  Support for TI's DaVinci platform.
 

arch/arm/common/Kconfig

@@ -12,7 +12,8 @@ config ICST307
 
 config SA1111
 	bool
-	select DMABOUNCE
+	select DMABOUNCE if !ARCH_PXA
+	select ZONE_DMA if !ARCH_PXA
 
 config DMABOUNCE
 	bool

arch/arm/include/asm/memory.h

@@ -137,6 +137,8 @@
 
 #ifndef arch_adjust_zones
 #define arch_adjust_zones(node,size,holes) do { } while (0)
+#elif !defined(CONFIG_ZONE_DMA)
+#error "custom arch_adjust_zones() requires CONFIG_ZONE_DMA"
 #endif
 
 /*

arch/arm/mach-pxa/Kconfig

@@ -210,6 +210,7 @@ config MACH_ARMCORE
 	bool "CompuLab CM-X270 modules"
 	select PXA27x
 	select IWMMXT
+	select ZONE_DMA if PCI
 
 config MACH_MAGICIAN
 	bool "Enable HTC Magician Support"