On Wed, 4 May 2011 17:59:29 -0400
Matt Turner <mattst88@xxxxxxxxx> wrote:
> Other architectures define this differently.
>
> arch/ia64/include/asm/dma-mapping.h:#define DMA_ERROR_CODE 0
> arch/microblaze/include/asm/dma-mapping.h:#define DMA_ERROR_CODE
> (~(dma_addr_t)0x0)
> arch/powerpc/include/asm/dma-mapping.h:#define DMA_ERROR_CODE
> (~(dma_addr_t)0x0)
> arch/sparc/include/asm/dma-mapping.h:#define DMA_ERROR_CODE
> (~(dma_addr_t)0x0)
> arch/x86/include/asm/dma-mapping.h:#define DMA_ERROR_CODE 0
>
> Any idea what the reason is?
Because an invalid DMA address is architecture specific. To be exact,
an invalid DMA address is DMA operation specific.
As I wrote in another mail, this patch is wrong.
Architectures don't need to define DMA_ERROR_CODE.
Some architectures need multiple dma_mapping_error functions. You
could use DMA_ERROR_CODE in order to avoid duplicated code like
this. That is, you define only for dma_map_ops that needs the own
mapping_error function.
static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
struct dma_map_ops *ops = get_dma_ops(dev);
if (ops->mapping_error)
return ops->mapping_error(dev, dma_addr);
return (dma_addr == DMA_ERROR_CODE);
}
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