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Diffstat (limited to 'recipes/u-boot/u-boot-git/nokia900/0001-ARM-Avoid-compiler-optimization-for-usages-of-readb-.patch')
-rw-r--r-- | recipes/u-boot/u-boot-git/nokia900/0001-ARM-Avoid-compiler-optimization-for-usages-of-readb-.patch | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/recipes/u-boot/u-boot-git/nokia900/0001-ARM-Avoid-compiler-optimization-for-usages-of-readb-.patch b/recipes/u-boot/u-boot-git/nokia900/0001-ARM-Avoid-compiler-optimization-for-usages-of-readb-.patch new file mode 100644 index 0000000000..73ce36aff7 --- /dev/null +++ b/recipes/u-boot/u-boot-git/nokia900/0001-ARM-Avoid-compiler-optimization-for-usages-of-readb-.patch @@ -0,0 +1,61 @@ +From a6154b8604c4cf1c9c44cf15524102e4e258a238 Mon Sep 17 00:00:00 2001 +From: Alexander Holler <holler@ahsoftware.de> +Date: Wed, 22 Dec 2010 01:04:22 +0000 +Subject: [PATCH] ARM: Avoid compiler optimization for usages of readb, writeb and friends. + +gcc 4.5.1 seems to ignore (at least some) volatile definitions, +avoid that as done in the kernel. + +Reading C99 6.7.3 8 and the comment 114) there, I think it is a bug of that +gcc version to ignore the volatile type qualifier used e.g. in __arch_getl(). +Anyway, using a definition as in the kernel headers avoids such optimizations when +gcc 4.5.1 is used. + +Maybe the headers as used in the current linux-kernel should be used, +but to avoid large changes, I've just added a small change to the current headers. + +I haven't add the definitions which are using a memory barrier because I haven't found +a place in the kernel where they were actually enabled (CONFIG_ARM_DMA_MEM_BUFFERABLE). + +Signed-off-by: Alexander Holler <holler@ahsoftware.de> +Signed-off-by: Wolfgang Denk <wd@denx.de> +Acked-by: Dirk Behme <dirk.behme@googlemail.com> +--- + arch/arm/include/asm/io.h | 20 ++++++++++++++------ + 1 files changed, 14 insertions(+), 6 deletions(-) + +diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h +index ff1518e..068ed17 100644 +--- a/arch/arm/include/asm/io.h ++++ b/arch/arm/include/asm/io.h +@@ -125,13 +125,21 @@ extern inline void __raw_readsl(unsigned int addr, void *data, int longlen) + #define __raw_readw(a) __arch_getw(a) + #define __raw_readl(a) __arch_getl(a) + +-#define writeb(v,a) __arch_putb(v,a) +-#define writew(v,a) __arch_putw(v,a) +-#define writel(v,a) __arch_putl(v,a) ++/* ++ * TODO: The kernel offers some more advanced versions of barriers, it might ++ * have some advantages to use them instead of the simple one here. ++ */ ++#define dmb() __asm__ __volatile__ ("" : : : "memory") ++#define __iormb() dmb() ++#define __iowmb() dmb() ++ ++#define writeb(v,c) do { __iowmb(); __arch_putb(v,c); } while (0) ++#define writew(v,c) do { __iowmb(); __arch_putw(v,c); } while (0) ++#define writel(v,c) do { __iowmb(); __arch_putl(v,c); } while (0) + +-#define readb(a) __arch_getb(a) +-#define readw(a) __arch_getw(a) +-#define readl(a) __arch_getl(a) ++#define readb(c) ({ u8 __v = __arch_getb(c); __iormb(); __v; }) ++#define readw(c) ({ u16 __v = __arch_getw(c); __iormb(); __v; }) ++#define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; }) + + /* + * The compiler seems to be incapable of optimising constants +-- +1.7.3.4 + |