From: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To: dmaengine@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Vinod Koul <vkoul@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Subject: [PATCH] dmaengine: Clarify cyclic transfer residue documentation
Date: Thu, 31 Mar 2022 15:41:14 +0200 [thread overview]
Message-ID: <20220331134114.703782-1-paul.kocialkowski@bootlin.com> (raw)
The current documentation for the residue reported in a cyclic transfer
case mentions that the reported residue should be relative to the current
period only. However the definition of DMA_RESIDUE_GRANULARITY_SEGMENT
specifies that the residue should be updated after each period for
a cyclic transfer, which is in direct contradiction.
Moreover the pcm_dmaengine common code uses the residue relative to
the whole cyclic buffer size, not one period.
Correct the residue-related documentation to reflect this.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
---
Documentation/driver-api/dmaengine/provider.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
index 0072c9c7efd3..d3fa80e333b1 100644
--- a/Documentation/driver-api/dmaengine/provider.rst
+++ b/Documentation/driver-api/dmaengine/provider.rst
@@ -457,7 +457,7 @@ supported.
- Should use dma_set_residue to report it
- In the case of a cyclic transfer, it should only take into
- account the current period.
+ account the total size of the cyclic buffer.
- Should return DMA_OUT_OF_ORDER if the device does not support in order
completion and is completing the operation out of order.
--
2.35.1
next reply other threads:[~2022-03-31 13:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 13:41 Paul Kocialkowski [this message]
2022-04-11 13:46 ` [PATCH] dmaengine: Clarify cyclic transfer residue documentation Vinod Koul
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