dma-direct: comment the dma_direct_free calling convention

Signed-off-by: Christoph Hellwig <[email protected]>
zarubaf · Feb 12, 2018 · 42ed645 · 42ed645
1 parent f25e6f6
commit 42ed645
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/lib/dma-direct.c b/lib/dma-direct.c
@@ -84,6 +84,10 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 	return page_address(page);
 }
 
+/*
+ * NOTE: this function must never look at the dma_addr argument, because we want
+ * to be able to use it as a helper for iommu implementations as well.
+ */
 void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
 		dma_addr_t dma_addr, unsigned long attrs)
 {