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| author | Federico Vaga <federico.vaga@cern.ch> | 2019-02-08 16:30:38 +0100 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2019-02-11 17:23:32 +0530 |
| commit | 85ed4f43db866fe1ea90bcca8cd1e5e628f04a6f (patch) | |
| tree | e72f9e3e75905245439d6f8008e7dbf2dd52916f /Documentation/driver-api | |
| parent | b29715966a2e13cc1dec22d3b50f3135db9591cd (diff) | |
| download | lwn-85ed4f43db866fe1ea90bcca8cd1e5e628f04a6f.tar.gz lwn-85ed4f43db866fe1ea90bcca8cd1e5e628f04a6f.zip | |
Documentation :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: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'Documentation/driver-api')
| -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..45953f171500 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. + Consequently, 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 |