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Re: memcpy and prefetch

To: ralf@linux-mips.org
Subject: Re: memcpy and prefetch
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Thu, 29 Jan 2009 21:36:13 +0900 (JST)
Cc: ddaney@caviumnetworks.com, msundius@cisco.com, linux-mips@linux-mips.org, dvomlehn@cisco.com, msundius@sundius.com
In-reply-to: <20090128183047.GA1691@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20090128103753.GC2234@linux-mips.org> <20090129.002850.118974677.anemo@mba.ocn.ne.jp> <20090128183047.GA1691@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
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

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