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authorSakari Ailus <sakari.ailus@iki.fi>2015-09-23 14:41:09 +0300
committerJonathan Corbet <corbet@lwn.net>2015-09-24 15:50:06 -0600
commit7bc590b2fc057f3c48b618c739517bf1af9a28fe (patch)
treeff8516085cd5098e5e0fcf83e3d72fe6564cc40c /Documentation/DMA-API-HOWTO.txt
parentc604503192718b9676a0ef5dd104b6a8acef8278 (diff)
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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>
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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
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