Documentation: DMA API: Be more explicit that nents is always the same

The nents 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@linux.intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 55b70b903ead..d69b3fc64e14 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