On Fri, Jul 13, 2012 at 1:01 PM, Laura Abbott lauraa@codeaurora.org wrote:
There are currently no dma allocation APIs that support cached buffers. For some use cases, caching provides a signficiant performance boost that beats write-combining regions. Add apis to allocate and map a cached DMA region.
btw, there were recent patches for allocating dma memory without a virtual mapping. With this you could map however you want to userspace (for example, cached)
I'm assuming that you are not needing it to be mapped cached to kernel?
BR, -R
Signed-off-by: Laura Abbott lauraa@codeaurora.org
arch/arm/include/asm/dma-mapping.h | 21 +++++++++++++++++++++ arch/arm/mm/dma-mapping.c | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h index dc988ff..1565403 100644 --- a/arch/arm/include/asm/dma-mapping.h +++ b/arch/arm/include/asm/dma-mapping.h @@ -239,12 +239,33 @@ int dma_mmap_coherent(struct device *, struct vm_area_struct *, extern void *dma_alloc_writecombine(struct device *, size_t, dma_addr_t *, gfp_t);
+/**
- dma_alloc_cached - allocate cached memory for DMA
- @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
- @size: required memory size
- @handle: bus-specific DMA address
- Allocate some cached memory for a device for
- performing DMA. This function allocates pages, and will
- return the CPU-viewed address, and sets @handle to be the
- device-viewed address.
- */
+extern void *dma_alloc_cached(struct device *, size_t, dma_addr_t *,
gfp_t);#define dma_free_writecombine(dev,size,cpu_addr,handle) \ dma_free_coherent(dev,size,cpu_addr,handle)
+#define dma_free_cached(dev,size,cpu_addr,handle) \
dma_free_coherent(dev,size,cpu_addr,handle)int dma_mmap_writecombine(struct device *, struct vm_area_struct *, void *, dma_addr_t, size_t);
+int dma_mmap_cached(struct device *, struct vm_area_struct *,
void *, dma_addr_t, size_t);/*
- This can be called during boot to increase the size of the consistent
- DMA region above it's default value of 2MB. It must be called before the
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index b1911c4..f396ddc 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -633,6 +633,20 @@ dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_ } EXPORT_SYMBOL(dma_alloc_writecombine);
+/*
- Allocate a cached DMA region
- */
+void * +dma_alloc_cached(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) +{
return __dma_alloc(dev, size, handle, gfp,pgprot_kernel,__builtin_return_address(0));+} +EXPORT_SYMBOL(dma_alloc_cached);
static int dma_mmap(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { @@ -664,6 +678,13 @@ int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma, } EXPORT_SYMBOL(dma_mmap_writecombine);
+int dma_mmap_cached(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size)+{
return dma_mmap(dev, vma, cpu_addr, dma_addr, size);+} +EXPORT_SYMBOL(dma_mmap_cached);
/*
- Free a buffer as defined by the above mapping.
-- 1.7.8.3
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