evie/android_kernel_oneplus_msm8998
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arm: Add option to skip buffer zeroing

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The DMA framework currently zeros all buffers because it (righfully so)
assumes that drivers will soon need to pass the memory to a device.
Some devices/use case may not require zeroed memory and there can
be an increase in performance if we skip the zeroing. Add a DMA_ATTR
to allow skipping of DMA zeroing.

Change-Id: Ib78a19cb341c3c441f91d5b004c6375c80c10413
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
[pdaly@codeaurora.org Resolve minor conflicts]
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
This commit is contained in:
Laura Abbott 2014-05-22 14:38:48 -07:00 • committed by David Keitel
parent f01c05b169
commit 0bf6f5ab15
1 changed files with 10 additions and 5 deletions
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15
arch/arm/mm/dma-mapping.c
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@ -310,7 +310,8 @@ static void __dma_free_buffer(struct page *page, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
const void *caller, bool want_vaddr);
const void *caller,
struct dma_attrs *attrs);
static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
pgprot_t prot, struct page **ret_page,
@ -378,7 +379,7 @@ static int __init atomic_pool_init(void)
if (dev_get_cma_area(NULL))
ptr = __alloc_from_contiguous(NULL, atomic_pool_size, prot,
&page, atomic_pool_init, true);
&page, atomic_pool_init, NULL);
else
ptr = __alloc_remap_buffer(NULL, atomic_pool_size, gfp, prot,
&page, atomic_pool_init, true);
@ -560,18 +561,22 @@ static int __free_from_pool(void *start, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
const void *caller, bool want_vaddr)
const void *caller,
struct dma_attrs *attrs)
{
unsigned long order = get_order(size);
size_t count = size >> PAGE_SHIFT;
struct page *page;
void *ptr = NULL;
bool want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING,
attrs);
page = dma_alloc_from_contiguous(dev, count, order);
if (!page)
return NULL;
__dma_clear_buffer(page, size);
if (!dma_get_attr(DMA_ATTR_SKIP_ZEROING, attrs))
__dma_clear_buffer(page, size);
if (!want_vaddr)
goto out;
@ -688,7 +693,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
addr = __alloc_simple_buffer(dev, size, gfp, &page);
else if (dev_get_cma_area(dev) && (gfp & __GFP_DIRECT_RECLAIM))
addr = __alloc_from_contiguous(dev, size, prot, &page,
caller, want_vaddr);
caller, attrs);
else if (is_coherent)
addr = __alloc_simple_buffer(dev, size, gfp, &page);
else if (!gfpflags_allow_blocking(gfp))