On Monday 20 June 2011, Marek Szyprowski wrote: > This patch modifies dma-mapping implementation on ARM architecture to > use common dma_map_ops structure and asm-generic/dma-mapping-common.h > helpers. > > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> This is a good idea in general, but I have a few concerns about details: First of all, should we only allow using dma_map_ops on ARM, or do we also want to support a case where these are all inlined as before? I suppose for the majority of the cases, the overhead of the indirect function call is near-zero, compared to the overhead of the cache management operation, so it would only make a difference for coherent systems without an IOMMU. Do we care about micro-optimizing those? > diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h > index 799669d..f4e4968 100644 > --- a/arch/arm/include/asm/dma-mapping.h > +++ b/arch/arm/include/asm/dma-mapping.h > @@ -10,6 +10,27 @@ > #include <asm-generic/dma-coherent.h> > #include <asm/memory.h> > > +extern struct dma_map_ops dma_ops; > + > +static inline struct dma_map_ops *get_dma_ops(struct device *dev) > +{ > + if (dev->archdata.dma_ops) > + return dev->archdata.dma_ops; > + return &dma_ops; > +} I would not name the global structure just 'dma_ops', the identifier could too easily conflict with a local variable in some driver. How about arm_dma_ops or linear_dma_ops instead? > /* > * The scatter list versions of the above methods. > */ > -extern int dma_map_sg(struct device *, struct scatterlist *, int, > - enum dma_data_direction); > -extern void dma_unmap_sg(struct device *, struct scatterlist *, int, > +extern int arm_dma_map_sg(struct device *, struct scatterlist *, int, > + enum dma_data_direction, struct dma_attrs *attrs); > +extern void arm_dma_unmap_sg(struct device *, struct scatterlist *, int, > + enum dma_data_direction, struct dma_attrs *attrs); > +extern void arm_dma_sync_sg_for_cpu(struct device *, struct scatterlist *, int, > enum dma_data_direction); > -extern void dma_sync_sg_for_cpu(struct device *, struct scatterlist *, int, > +extern void arm_dma_sync_sg_for_device(struct device *, struct scatterlist *, int, > enum dma_data_direction); > -extern void dma_sync_sg_for_device(struct device *, struct scatterlist *, int, > - enum dma_data_direction); > - You should not need to make these symbols visible in the header file any more unless they are used outside of the main file later. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html