From db693aded3fb419c763963246281e417c1c0e126 Mon Sep 17 00:00:00 2001
From: Federico Vaga <federico.vaga@cern.ch>
Date: Fri, 8 Feb 2019 16:30:38 +0100
Subject: [PATCH] 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>
---
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 fbbb2831f29f8..d728e50105eb3 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
--
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