linux-kernel - Re: [PATCH 20/32] Blackfin arch: dma

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Message-ID: <84144f020705210426w1704e133k2559f8ceffe9268c@mail.gmail.com>
Date:	Mon, 21 May 2007 14:26:01 +0300
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Bryan Wu" <bryan.wu@...log.com>
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, "Aubrey Li" <aubrey.li@...log.com>
Subject: Re: [PATCH 20/32] Blackfin arch: dma_memcpy borken for > 64K

Hi Bryan,

On 5/21/07, Bryan Wu <bryan.wu@...log.com> wrote:
> -void *dma_memcpy(void *dest, const void *src, size_t size)
> +void *_dma_memcpy(void *dest, const void *src, size_t size)

Minor nitpick: the established naming convention is two underscores, not one.

> +void *dma_memcpy(void *dest, const void *src, size_t size)
> +{
> +       size_t bulk;
> +       size_t rest;
> +       void * addr;
> +
> +       bulk = (size >> 16) << 16;

I assume this is significantly faster on your architecture than:

   bulk = size & ~0xFFFFUL;

which is more readable?

> +       rest = size - bulk;
> +       if (bulk)
> +               _dma_memcpy(dest, src, bulk);
> +       addr = _dma_memcpy(dest+bulk, src+bulk, rest);
> +       return addr;

Does this work for 128K and up? Why?
-
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