Messages in this thread Patch in this message | | | From | Lorenzo Nava <> | Subject | [PATCH v4] arm DMA: Fix allocation from CMA for coherent DMA | Date | Mon, 29 Jun 2015 19:10:45 +0200 |
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This patch allows the use of CMA for DMA coherent memory allocation. At the moment if the input parameter "is_coherent" is set to true the allocation is not made using the CMA, which I think is not the desired behaviour.
Signed-off-by: Lorenzo Nava <lorenx4@xxxxxxxx> --- Changes in v2: correct __arm_dma_free() according to __dma_alloc() allocation --- Changes in v3: now __dma_alloc(), if 'is_coherent' is true, returns memory from CMA if there is no need for atomic allocation. If CMA is not available the function returns the result of __alloc_simple_buffer(). __arm_dma_free() frees memory according to the new alloc function avoiding __dma_free_remap() for coherent DMA if CMA is not enable. arm_dma_alloc() mark pages as cacheable if attrs are set by default to NULL. If attrs is not NULL, attributes are preserved in the allocation.
Coherent allocation tested on Xilinx Zynq processor. --- Changes in v4: back to "if..else" code style for __dma_alloc() avoided unnecessary __free_from_pool() call in __arm_dma_free() --- arch/arm/mm/dma-mapping.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 7e7583d..7d4bcf5 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -645,14 +645,18 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, size = PAGE_ALIGN(size); want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs); - if (is_coherent || nommu()) + if (nommu()) + addr = __alloc_simple_buffer(dev, size, gfp, &page); + else if (dev_get_cma_area(dev) && (gfp & __GFP_WAIT)) + addr = __alloc_from_contiguous(dev, size, prot, &page, + caller, want_vaddr); + else if (is_coherent) addr = __alloc_simple_buffer(dev, size, gfp, &page); else if (!(gfp & __GFP_WAIT)) addr = __alloc_from_pool(size, &page); - else if (!dev_get_cma_area(dev)) - addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller, want_vaddr); else - addr = __alloc_from_contiguous(dev, size, prot, &page, caller, want_vaddr); + addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, + caller, want_vaddr); if (page) *handle = pfn_to_dma(dev, page_to_pfn(page)); @@ -680,9 +684,14 @@ void *arm_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, static void *arm_coherent_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs) { - pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL); + pgprot_t prot; void *memory; + if (attrs == NULL) + prot = PAGE_KERNEL; + else + prot = __get_dma_pgprot(attrs, PAGE_KERNEL); + if (dma_alloc_from_coherent(dev, size, handle, &memory)) return memory; @@ -735,12 +744,12 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr, size = PAGE_ALIGN(size); - if (is_coherent || nommu()) { + if (nommu()) { __dma_free_buffer(page, size); - } else if (__free_from_pool(cpu_addr, size)) { + } else if (!is_coherent && __free_from_pool(cpu_addr, size)) { return; } else if (!dev_get_cma_area(dev)) { - if (want_vaddr) + if (want_vaddr && !is_coherent) __dma_free_remap(cpu_addr, size); __dma_free_buffer(page, size); } else { -- 1.7.10.4
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