On 22.12.2010 12:04, Alexander Holler wrote: > 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<hol...@ahsoftware.de>
This patch seems to be the same as the proposal from Wolfgang http://lists.denx.de/pipermail/u-boot/2010-December/084122.html So we shouldn't drop his Signed-off-by: Wolfgang Denk <w...@denx.de> Besides of this Acked-by: Dirk Behme <dirk.be...@googlemail.com> Thanks Dirk > --- > 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 _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
