From 1f854536a8336c61c89ab040bbc874c75325d37c Mon Sep 17 00:00:00 2001 From: Paul Kocialkowski Date: Thu, 31 Mar 2022 15:41:14 +0200 Subject: [PATCH] dmaengine: Clarify cyclic transfer residue documentation 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 Link: https://lore.kernel.org/r/20220331134114.703782-1-paul.kocialkowski@bootlin.com Signed-off-by: Vinod Koul --- 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 0072c9c..d3fa80e 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. -- 2.7.4