Messages in this thread Patch in this message | | | From | Paul Kocialkowski <> | Subject | [PATCH] dmaengine: Clarify cyclic transfer residue documentation | Date | Thu, 31 Mar 2022 15:41:14 +0200 |
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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
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