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authorVinod Koul <vinod.koul@intel.com>2015-08-05 08:42:04 +0530
committerVinod Koul <vinod.koul@intel.com>2015-08-17 13:46:22 +0530
commit06f10e2f936424496d44e5541c220845c8c55345 (patch)
tree5ae6aea36ea8370ec4ae1e0abadcafadb87eddf0 /Documentation/dmaengine
parent09659a5978e16a7f3676fd6cb41e21daa77ce9a6 (diff)
downloadlinux-aarch64-06f10e2f936424496d44e5541c220845c8c55345.tar.gz
Documentation: dmaengine: fix the DMA_CTRL_ACK documentation
As discussed recently the meaning of DMA_CTRL_ACK is that a desc cannot be reused by provider until the client acknowledges receipt, i.e. has has a chance to establish any dependency chains. So update documentation Signed-off-by: Vinod Koul <vinod.koul@intel.com> Acked-by:Robert Jarzmik <robert.jarzmik@free.fr>
Diffstat (limited to 'Documentation/dmaengine')
-rw-r--r--Documentation/dmaengine/provider.txt12
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt
index ca67b0f04c6e..243889ec5c5a 100644
--- a/Documentation/dmaengine/provider.txt
+++ b/Documentation/dmaengine/provider.txt
@@ -345,12 +345,12 @@ where to put them)
that abstracts it away.
* DMA_CTRL_ACK
- - If set, the transfer can be reused after being completed.
- - There is a guarantee the transfer won't be freed until it is acked
- by async_tx_ack().
- - As a consequence, if a device driver wants to skip the dma_map_sg() and
- dma_unmap_sg() in between 2 transfers, because the DMA'd data wasn't used,
- it can resubmit the transfer right after its completion.
+ - If clear, the descriptor cannot be reused by provider until the
+ client acknowledges receipt, i.e. has has a chance to establish any
+ dependency chains
+ - This can be acked by invoking async_tx_ack()
+ - If set, does not mean descriptor can be reused
+
General Design Notes
--------------------