X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fdma-coherent.c;h=c1d4d5b4c61ccb6fb95262fc34c2166158e00cd3;hb=ff9bc512f198eb47204f55b24c6fe3d36ed89592;hp=89a554cfd936b57573eb3c240ceb78b764ef1824;hpb=f6dc8ccaab6d8f63cbae1e6c73fe972b26f5376c;p=linux-2.6

diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
index 89a554cfd9..c1d4d5b4c6 100644
--- a/kernel/dma-coherent.c
+++ b/kernel/dma-coherent.c
@@ -77,21 +77,35 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
 {
 	struct dma_coherent_mem *mem = dev->dma_mem;
 	int pos, err;
-	int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1);
 
-	pages >>= PAGE_SHIFT;
+	size += device_addr & ~PAGE_MASK;
 
 	if (!mem)
 		return ERR_PTR(-EINVAL);
 
 	pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
-	err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
+	err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
 	if (err != 0)
 		return ERR_PTR(err);
 	return mem->virt_base + (pos << PAGE_SHIFT);
 }
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
+/**
+ * dma_alloc_from_coherent() - 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)
 {
@@ -105,13 +119,25 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 			*dma_handle = mem->device_base + (page << PAGE_SHIFT);
 			*ret = mem->virt_base + (page << PAGE_SHIFT);
 			memset(*ret, 0, size);
-		}
-		if (mem->flags & DMA_MEMORY_EXCLUSIVE)
+		} else if (mem->flags & DMA_MEMORY_EXCLUSIVE)
 			*ret = NULL;
 	}
 	return (mem != NULL);
 }
 
+/**
+ * dma_release_from_coherent() - 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;