Re: [PATCH 1/8] add map_page and unmap_page to struct dma_mapping_ops

[Joerg Roedel <joro@8bytes.org>]

On Mon, Jan 05, 2009 at 11:47:21PM +0900, FUJITA Tomonori wrote:
> This patch adds map_page and unmap_page to struct dma_mapping_ops.
> 
> This is a preparation of struct dma_mapping_ops unification. We use
> map_page and unmap_page instead of map_single and unmap_single.
> 
> We will remove map_single and unmap_single hooks in the last patch in
> this patchset.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> ---
>  arch/x86/include/asm/dma-mapping.h |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
> index e93265c..2f89d2e 100644
> --- a/arch/x86/include/asm/dma-mapping.h
> +++ b/arch/x86/include/asm/dma-mapping.h
> @@ -8,6 +8,7 @@
>  
>  #include <linux/kmemcheck.h>
>  #include <linux/scatterlist.h>
> +#include <linux/dma-attrs.h>
>  #include <asm/io.h>
>  #include <asm/swiotlb.h>
>  #include <asm-generic/dma-coherent.h>
> @@ -51,6 +52,13 @@ struct dma_mapping_ops {
>  	void            (*unmap_sg)(struct device *hwdev,
>  				struct scatterlist *sg, int nents,
>  				int direction);
> +	dma_addr_t	(*map_page)(struct device *dev, struct page *page,
> +				    unsigned long offset, size_t size,
> +				    enum dma_data_direction dir,
> +				    struct dma_attrs *attrs);
> +	void 		(*unmap_page)(struct device *dev, dma_addr_t dma_handle,
> +				      size_t size, enum dma_data_direction dir,
> +				      struct dma_attrs *attrs);

Why do we need an offset into the page? The name suggests that this
function maps a whole page so the offset should be irrelevant.

Joerg