From 85ed4f43db866fe1ea90bcca8cd1e5e628f04a6f Mon Sep 17 00:00:00 2001 From: Federico Vaga Date: Fri, 8 Feb 2019 16:30:38 +0100 Subject: [PATCH] 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 Signed-off-by: Vinod Koul --- Documentation/driver-api/dmaengine/client.rst | 7 +++++++ 1 file changed, 7 insertions(+) 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