From: Federico Vaga <federico.vaga@cern.ch>
To: Vinod Koul <vkoul@kernel.org>, Jonathan Corbet <corbet@lwn.net>
Cc: <dmaengine@vger.kernel.org>, <linux-doc@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
Federico Vaga <federico.vaga@cern.ch>
Subject: [PATCH] doc:dmaengine: clarify DMA desc. pointer after submission
Date: Fri, 8 Feb 2019 16:30:38 +0100 [thread overview]
Message-ID: <20190208153038.23272-1-federico.vaga@cern.ch> (raw)
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>
---
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..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
--
2.15.0
next reply other threads:[~2019-02-08 15:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 15:30 Federico Vaga [this message]
2019-02-11 11:54 ` [PATCH] doc:dmaengine: clarify DMA desc. pointer after submission Vinod Koul
2019-02-11 12:10 ` Federico Vaga
2019-02-11 15:40 ` Jonathan Corbet
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