[PATCH] ARM: optimize memset_io()/memcpy_fromio()/memcpy_toio()

[Dirk Behme]

On 28.09.2012 00:02, Russell King wrote:
> If we are building for a LE platform, and we haven't overriden the
> MMIO ops, then we can optimize the mem*io operations using the
> standard string functions.
>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> ---
>   arch/arm/include/asm/io.h |   25 +++++++++++++++++++++++++
>   1 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index 815c669..ed0577e 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -23,6 +23,7 @@
>
>   #ifdef __KERNEL__
>
> +#include <linux/string.h>
>   #include <linux/types.h>
>   #include <asm/byteorder.h>
>   #include <asm/memory.h>
> @@ -249,9 +250,33 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
>   #define writesw(p,d,l)		__raw_writesw(p,d,l)
>   #define writesl(p,d,l)		__raw_writesl(p,d,l)
>
> +#ifndef __ARMBE__
> +static inline void memset_io(volatile void __iomem *dst, unsigned c,
> +	size_t count)
> +{
> +	memset((void __force *)dst, c, count);
> +}
> +#define memset_io(dst,c,count) memset_io(dst,c,count)
> +
> +static inline void memcpy_fromio(void *to, const volatile void __iomem *from,
> +	size_t count)
> +{
> +	memcpy(to, (const void __force *)from, count);
> +}
> +#define memcpy_fromio(to,from,count) memcpy_fromio(to,from,count)
> +
> +static inline void memcpy_toio(volatile void __iomem *to, const void *from,
> +	size_t count)
> +{
> +	memcpy((void __force *)to, from, count);
> +}
> +#define memcpy_toio(to,from,count) memcpy_toio(to,from,count)
> +
> +#else
>   #define memset_io(c,v,l)	_memset_io(c,(v),(l))
>   #define memcpy_fromio(a,c,l)	_memcpy_fromio((a),c,(l))
>   #define memcpy_toio(c,a,l)	_memcpy_toio(c,(a),(l))
> +#endif
>
>   #endif	/* readl */

I'd like to ask if there is any chance to get anything like this or the 
even older proposal

http://lists.infradead.org/pipermail/linux-arm-kernel/2009-November/004077.html

merged? Maybe an updated version incorporating the discussion conclusions?


In the discussion of

http://lists.infradead.org/pipermail/linux-arm-kernel/2009-November/004077.html

there have been some doubts if it's a good idea to enable it for all 
SoCs. Therefore that patch introduced a

config OPTIMIZED_IOMEM_MEMCPY

which would allow us to enable it for only known to be compatible SoCs. 
Just in case this helps to get it applied ;)


Many thanks and best regards

Dirk