[PATCH] [RFC] drivers: dma-coherent: pass struct dma_attrs to dma_alloc_from_coherent

From: Jaewon Kim
Date: Fri Dec 09 2016 - 00:05:40 EST


dma_alloc_from_coherent does not get struct dma_attrs information.
If dma_attrs information is passed to dma_alloc_from_coherent,
dma_alloc_from_coherent can do more jobs accodring to the information.
As a example I added DMA_ATTR_SKIP_ZEROING to skip zeroing. Accoring
to driver implementation ZEROING could be skipped or could be done later.

Signed-off-by: Jaewon Kim <jaewon31.kim@xxxxxxxxxxx>
---
drivers/base/dma-coherent.c | 6 +++++-
include/linux/dma-mapping.h | 7 ++++---
2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 640a7e6..428eced 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -151,6 +151,7 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
* @dma_handle: This will be filled with the correct dma handle
* @ret: This pointer will be filled with the virtual address
* to allocated area.
+ * @attrs: dma_attrs to pass additional information
*
* This function should be only called from per-arch dma_alloc_coherent()
* to support allocation from per-device coherent memory pools.
@@ -159,7 +160,8 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
* generic memory areas, or !0 if dma_alloc_coherent should return @ret.
*/
int dma_alloc_from_coherent(struct device *dev, ssize_t size,
- dma_addr_t *dma_handle, void **ret)
+ dma_addr_t *dma_handle, void **ret,
+ struct dma_attrs *attrs)
{
struct dma_coherent_mem *mem;
int order = get_order(size);
@@ -190,6 +192,8 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
*ret = mem->virt_base + (pageno << PAGE_SHIFT);
dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
spin_unlock_irqrestore(&mem->spinlock, flags);
+ if (dma_get_attr(DMA_ATTR_SKIP_ZEROING, attrs))
+ return 1;
if (dma_memory_map)
memset(*ret, 0, size);
else
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 08528af..737fd71 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -151,13 +151,14 @@ static inline int is_device_dma_capable(struct device *dev)
* Don't use them in device drivers.
*/
int dma_alloc_from_coherent(struct device *dev, ssize_t size,
- dma_addr_t *dma_handle, void **ret);
+ dma_addr_t *dma_handle, void **ret,
+ struct dma_attrs *attrs);
int dma_release_from_coherent(struct device *dev, int order, void *vaddr);

int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, size_t size, int *ret);
#else
-#define dma_alloc_from_coherent(dev, size, handle, ret) (0)
+#define dma_alloc_from_coherent(dev, size, handle, ret, attrs) (0)
#define dma_release_from_coherent(dev, order, vaddr) (0)
#define dma_mmap_from_coherent(dev, vma, vaddr, order, ret) (0)
#endif /* CONFIG_HAVE_GENERIC_DMA_COHERENT */
@@ -456,7 +457,7 @@ static inline void *dma_alloc_attrs(struct device *dev, size_t size,

BUG_ON(!ops);

- if (dma_alloc_from_coherent(dev, size, dma_handle, &cpu_addr))
+ if (dma_alloc_from_coherent(dev, size, dma_handle, &cpu_addr, attrs))
return cpu_addr;

if (!arch_dma_alloc_attrs(&dev, &flag))
--
1.9.1