ARM: Optionally allow ARMv6 to use 'normal, bufferable' memory for DMA

[net-next-2.6.git] / arch / arm / mm / Kconfig

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index baf638487a2d530acaf30c7cab9581b3ec5b6f47..573528d9c6d81b01000771e4af605f7042cb2292 100644 (file)
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -399,7 +399,7 @@ config CPU_V6
 config CPU_32v6K
        bool "Support ARM V6K processor extensions" if !SMP
        depends on CPU_V6
-       default y if SMP && !ARCH_MX3
+       default y if SMP && !(ARCH_MX3 || ARCH_OMAP2)
        help
          Say Y here if your ARMv6 processor supports the 'K' extension.
          This enables the kernel to use some instructions not present
@@ -410,7 +410,7 @@ config CPU_32v6K
 # ARMv7
 config CPU_V7
        bool "Support ARM V7 processor" if ARCH_INTEGRATOR || MACH_REALVIEW_EB || MACH_REALVIEW_PBX
-       select CPU_32v6K
+       select CPU_32v6K if !ARCH_OMAP2
        select CPU_32v7
        select CPU_ABRT_EV7
        select CPU_PABRT_V7
@@ -754,7 +754,7 @@ config CACHE_FEROCEON_L2_WRITETHROUGH
 config CACHE_L2X0
        bool "Enable the L2x0 outer cache controller"
        depends on REALVIEW_EB_ARM11MP || MACH_REALVIEW_PB11MP || MACH_REALVIEW_PB1176 || \
-                  REALVIEW_EB_A9MP || ARCH_MX35 || ARCH_MX31 || MACH_REALVIEW_PBX || ARCH_NOMADIK
+                  REALVIEW_EB_A9MP || ARCH_MX35 || ARCH_MX31 || MACH_REALVIEW_PBX || ARCH_NOMADIK || ARCH_OMAP4
        default y
        select OUTER_CACHE
        help
@@ -779,5 +779,24 @@ config CACHE_XSC3L2
 
 config ARM_L1_CACHE_SHIFT
        int
-       default 6 if ARCH_OMAP3 || ARCH_S5PC1XX
+       default 6 if ARM_L1_CACHE_SHIFT_6
        default 5
+
+config ARM_DMA_MEM_BUFFERABLE
+       bool "Use non-cacheable memory for DMA" if CPU_V6 && !CPU_V7
+       default y if CPU_V6 || CPU_V7
+       help
+         Historically, the kernel has used strongly ordered mappings to
+         provide DMA coherent memory.  With the advent of ARMv7, mapping
+         memory with differing types results in unpredictable behaviour,
+         so on these CPUs, this option is forced on.
+
+         Multiple mappings with differing attributes is also unpredictable
+         on ARMv6 CPUs, but since they do not have aggressive speculative
+         prefetch, no harm appears to occur.
+
+         However, drivers may be missing the necessary barriers for ARMv6,
+         and therefore turning this on may result in unpredictable driver
+         behaviour.  Therefore, we offer this as an option.
+
+         You are recommended say 'Y' here and debug any affected drivers.