Re: memcpy and prefetch

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

On Wed, 28 Jan 2009 18:30:47 +0000, Ralf Baechle <ralf@linux-mips.org> wrote:
> --- a/arch/mips/lib/memcpy.S
> +++ b/arch/mips/lib/memcpy.S
> @@ -21,7 +21,7 @@
>   * end of memory on some systems.  It's also a seriously bad idea on non
>   * dma-coherent systems.
>   */
> -#if !defined(CONFIG_DMA_COHERENT) || !defined(CONFIG_DMA_IP27)
> +#ifdef CONFIG_DMA_NONCOHERENT
>  #undef CONFIG_CPU_HAS_PREFETCH
>  #endif
>  #ifdef CONFIG_MIPS_MALTA

This makes IP27 (and all other coherent platforms) use prefetch.  Is
prefetch OK for all of them?

I suppose memcpy_fromio() should not use PREFETCH, at least.

---
Atsushi Nemoto