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| author | Federico Vaga <federico.vaga@cern.ch> | 2019-02-08 16:30:38 +0100 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2019-02-11 08:40:16 -0700 |
| commit | db693aded3fb419c763963246281e417c1c0e126 (patch) | |
| tree | fe7d307eb0af8517281cb9a8dcdf4daf42067c11 | |
| parent | 2c71d305caf9cd5076873c6a57d22ab8cb7c906c (diff) | |
doc:dmaengine: clarify DMA desc. pointer after submission
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: Jonathan Corbet <corbet@lwn.net>
| -rw-r--r-- | Documentation/driver-api/dmaengine/client.rst | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst index fbbb2831f29f..d728e50105eb 100644 --- a/Documentation/driver-api/dmaengine/client.rst +++ b/Documentation/driver-api/dmaengine/client.rst @@ -168,6 +168,13 @@ The details of these operations are: 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. + .. note:: + + After calling ``dmaengine_submit()`` the submitted transfer descriptor + (``struct dma_async_tx_descriptor``) belongs to the DMA engine. + Consequentially, the client must consider invalid the pointer to that + descriptor. + 5. Issue pending DMA requests and wait for callback notification The transactions in the pending queue can be activated by calling the |