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Documentation :dmaengine: clarify DMA desc. pointer after submission

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It clarifies that the DMA description pointer returned by
`dmaengine_prep_*` function should not be used after submission.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Federico Vaga 2019-02-08 16:30:38 +01:00 committed by Vinod Koul
parent b29715966a
commit 85ed4f43db
1 changed files with 7 additions and 0 deletions
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7
Documentation/driver-api/dmaengine/client.rst
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@ -168,6 +168,13 @@ The details of these operations are:
dmaengine_submit() will not start the DMA operation, it merely adds dmaengine_submit() will not start the DMA operation, it merely adds
it to the pending queue. For this, see step 5, dma_async_issue_pending. it to the pending queue. For this, see step 5, dma_async_issue_pending.
.. note::
After calling ``dmaengine_submit()`` the submitted transfer descriptor
(``struct dma_async_tx_descriptor``) belongs to the DMA engine.
Consequently, the client must consider invalid the pointer to that
descriptor.
5. Issue pending DMA requests and wait for callback notification 5. Issue pending DMA requests and wait for callback notification
The transactions in the pending queue can be activated by calling the The transactions in the pending queue can be activated by calling the