[PATCH 1/1] Documentation: DMA API: Be more explicit that nelems is always the same

[Sakari Ailus]

The nelems argument to the DMA API functions operating on scatterlists is
always the same. The documentation used different argument names and the
matter was not mentioned in Documentation/DMA-API-HOWTO.txt at all. Fix
these.

Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
 Documentation/DMA-API-HOWTO.txt | 5 +++++
 Documentation/DMA-API.txt       | 9 +++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 55b70b9..d69b3fc 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -681,6 +681,11 @@ or:
 
 as appropriate.
 
+PLEASE NOTE:  The 'nents' argument to dma_sync_sg_for_cpu() and
+	      dma_sync_sg_for_device() must be the same passed to
+	      dma_map_sg(). It is _NOT_ the count returned by
+	      dma_map_sg().
+
 After the last DMA transfer call one of the DMA unmap routines
 dma_unmap_{single,sg}(). If you don't touch the data from the first
 dma_map_*() call till dma_unmap_*(), then you don't have to call the
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index edccacd..8c832f0 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -340,14 +340,15 @@ accessed sg->address and sg->length as shown above.
 
 	void
 	dma_unmap_sg(struct device *dev, struct scatterlist *sg,
-		int nhwentries, enum dma_data_direction direction)
+		int nents, enum dma_data_direction direction)
 
 Unmap the previously mapped scatter/gather list.  All the parameters
 must be the same as those and passed in to the scatter/gather mapping
 API.
 
 Note: <nents> must be the number you passed in, *not* the number of
-DMA address entries returned.
+DMA address entries returned. In struct sg_table this is the field
+called orig_nents.
 
 void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
@@ -356,10 +357,10 @@ void
 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t size,
 			   enum dma_data_direction direction)
 void
-dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nelems,
+dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 		    enum dma_data_direction direction)
 void
-dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
+dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 		       enum dma_data_direction direction)
 
 Synchronise a single contiguous or scatter/gather mapping for the CPU

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@xxxxxx	XMPP: sailus@xxxxxxxxxxxxxx
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