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.
---
arch/arm/mm/dma-mapping.c | 35 +++++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 7e7583d..8e7f402 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -645,15 +645,29 @@ 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 (!(gfp & __GFP_WAIT))
+ goto dma_alloc_done;
+ }
+
+ if (dev_get_cma_area(dev) && (gfp & __GFP_WAIT)) {
+ addr = __alloc_from_contiguous(dev, size, prot, &page,
+ caller, want_vaddr);
+ goto dma_alloc_done;
+ }
+
+ if (is_coherent) {
+ addr = __alloc_simple_buffer(dev, size, gfp, &page);
+ goto dma_alloc_done;
+ }
+
+ 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);
+dma_alloc_done:
if (page)
*handle = pfn_to_dma(dev, page_to_pfn(page));
@@ -680,9 +694,14 @@ 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 +754,12 @@ 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)) {
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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