[PATCH 2/2] dma-coherent: add documentation to new interfaces
From: Dmitry Baryshkov
Date: Sun Jul 20 2008 - 07:01:29 EST
Signed-off-by: Dmitry Baryshkov <dbaryshkov@xxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
kernel/dma-coherent.c | 28 ++++++++++++++++++++++++++++
1 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
index 56dff5c..7517115 100644
@@ -92,6 +92,21 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
+ * Try to allocate memory from the per-device coherent area.
+ * @dev: device from which we allocate memory
+ * @size: size of requested memory area
+ * @dma_handle: This will be filled with the correct dma handle
+ * @ret: This pointer will be filled with the virtual address
+ * to allocated area.
+ * This function should be only called from per-arch %dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * 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)
@@ -111,6 +126,19 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
return (mem != NULL);
+ * Try to free the memory allocated from per-device coherent memory pool.
+ * @dev: device from which the memory was allocated
+ * @order: the order of pages allocated
+ * @vaddr: virtual address of allocated pages
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ * Returns 1 if we correctly released the memory, or 0 if
+ * %dma_release_coherent() should proceed with releasing memory from
+ * generic pools.
int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
With best wishes
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