[PATCH 3/8] ARM: dma-mapping: use asm-generic/dma-mapping-common.h
From: arnd@arndb.de (Arnd Bergmann)
Date: 2011-06-24 15:37:09
Also in:
linux-arch, linux-mm
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@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
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?
quoted hunk ↗ jump to hunk
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