From mboxrd@z Thu Jan 1 00:00:00 1970 From: lauraa@codeaurora.org (Laura Abbott) Date: Mon, 16 Jul 2012 18:06:49 -0700 Subject: [Linaro-mm-sig] [PATCH][RFC] arm: dma-mapping: Add support for allocating/mapping cached buffers In-Reply-To: References: <1342202506-12449-1-git-send-email-lauraa@codeaurora.org> <1342202506-12449-2-git-send-email-lauraa@codeaurora.org> Message-ID: <5004BAA9.5070903@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 7/14/2012 6:53 AM, Clark, Rob wrote: > On Fri, Jul 13, 2012 at 1:01 PM, Laura Abbott 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? > Thanks for reminding me about those patches. They don't quite solve the problem as is for two reasons: 1) I'm looking at regular CMA allocations, not iommu allocations which is what the patches covered 2) I do actually need a kernel cached mapping in addition to the userspace mappings. I've obviously missed the last DMA rework patches, and I should rebase/rework against those. Is another DMA attribute (DMA_ATTR_CACHED) an acceptable option? > BR, > -R > Thanks, Laura >> Signed-off-by: Laura Abbott >> --- >> 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 >> >> >> _______________________________________________ >> Linaro-mm-sig mailing list >> Linaro-mm-sig at lists.linaro.org >> http://lists.linaro.org/mailman/listinfo/linaro-mm-sig -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.