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| author | Vinod Koul <vinod.koul@intel.com> | 2015-08-05 05:12:04 +0200 |
|---|---|---|
| committer | Vinod Koul <vinod.koul@intel.com> | 2015-08-17 10:16:22 +0200 |
| commit | 06f10e2f936424496d44e5541c220845c8c55345 (patch) | |
| tree | 5ae6aea36ea8370ec4ae1e0abadcafadb87eddf0 | |
| parent | dmaengine: ioatdma: Clean up IOAT_COMPLETION_PENDING flag (diff) | |
| download | linux-06f10e2f936424496d44e5541c220845c8c55345.tar.xz linux-06f10e2f936424496d44e5541c220845c8c55345.zip | |
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>
| -rw-r--r-- | Documentation/dmaengine/provider.txt | 12 |
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 -------------------- |