Re: [PATCH -mm 09/12] blackfin: use use asm-generic/scatterlist.h

[Mike Frysinger <vapier.adi@gmail.com>]

On Mon, Apr 5, 2010 at 19:52, FUJITA Tomonori wrote:
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> Cc: Mike Frysinger <vapier@gentoo.org>
> ---
>  arch/blackfin/include/asm/scatterlist.h |   22 +---------------------
>  1 files changed, 1 insertions(+), 21 deletions(-)
>
> diff --git a/arch/blackfin/include/asm/scatterlist.h b/arch/blackfin/include/asm/scatterlist.h
> index 04f4487..64d41d3 100644
> --- a/arch/blackfin/include/asm/scatterlist.h
> +++ b/arch/blackfin/include/asm/scatterlist.h
> @@ -1,27 +1,7 @@
>  #ifndef _BLACKFIN_SCATTERLIST_H
>  #define _BLACKFIN_SCATTERLIST_H
>
> -#include <linux/mm.h>
> -
> -struct scatterlist {
> -#ifdef CONFIG_DEBUG_SG
> -       unsigned long sg_magic;
> -#endif
> -       unsigned long page_link;
> -       unsigned int offset;
> -       dma_addr_t dma_address;
> -       unsigned int length;
> -};
> -
> -/*
> - * These macros should be used after a pci_map_sg call has been done
> - * to get bus addresses of each of the SG entries and their lengths.
> - * You should only work with the number of sg entries pci_map_sg
> - * returns, or alternatively stop on the first sg_dma_len(sg) which
> - * is 0.
> - */
> -#define sg_dma_address(sg)      ((sg)->dma_address)
> -#define sg_dma_len(sg)          ((sg)->length)
> +#include <asm-generic/scatterlist.h>
>
>  #define ISA_DMA_THRESHOLD      (0xffffffff)

this is the same value as the common asm-generic one, so this define
should be punted, especially since this would probably introduce
redefined warnings.

once that is done, this header is simply a redirect, so it'd be better
if it was just one line:
#include <asm-generic/scatterlist.h>

one of the reasons i hadnt converted sooner was that it seems like the
common header introduces bloat.  the Blackfin header has just "length"
while the asm-generic has both "length" and "dma_length".  unless i
missed something, this hasnt been a problem for us.  perhaps the
common header should have something like:
#if __BITS_PER_LONG == 64
    unsigned int    dma_length;
#endif
this would match the existing sg_dma_len code.  or perhaps declare the
two lengths as an anonymous union.
-mike