iommu/io-pgtable: Improve documentation of .map_sg callback

The return value of the .map_sg callback is currently undocumented.
Document it.

Change-Id: I195cbfb78eaf173d916dd03190f89b2fe04e144e
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>

diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
index f74f148..5d3848a 100644 (file)
--- a/drivers/iommu/io-pgtable.h
+++ b/drivers/iommu/io-pgtable.h
@@ -77,7 +77,8 @@ struct io_pgtable_cfg {
  * struct io_pgtable_ops - Page table manipulation API for IOMMU drivers.
  *
  * @map:          Map a physically contiguous memory region.
- * @map_sg:      Map a scatterlist. The size parameter contains the size
+ * @map_sg:      Map a scatterlist.  Returns the number of bytes mapped,
+ *               or 0 on failure.  The size parameter contains the size
  *               of the partial mapping in case of failure.
  * @unmap:        Unmap a physically contiguous memory region.
  * @iova_to_phys: Translate iova to physical address.