From 9686218982709122373b755c9d7457bed0872999 Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Wed, 20 Jul 2016 13:14:19 -0700 Subject: dmaengine: documentation to the new callback mechanism Adding documentation in dmaengine/provider.txt on the usage of callback with result, callback_result, function pointer to retrieve transanction result from a DMA submission. Signed-off-by: Dave Jiang Reviewed-by: Lars-Peter Clausen Signed-off-by: Vinod Koul --- Documentation/dmaengine/provider.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'Documentation/dmaengine') diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt index 91ce82d5f0c4..c4fd47540b31 100644 --- a/Documentation/dmaengine/provider.txt +++ b/Documentation/dmaengine/provider.txt @@ -282,6 +282,17 @@ supported. that is supposed to push the current transaction descriptor to a pending queue, waiting for issue_pending to be called. + - In this structure the function pointer callback_result can be + initialized in order for the submitter to be notified that a + transaction has completed. In the earlier code the function pointer + callback has been used. However it does not provide any status to the + transaction and will be deprecated. The result structure defined as + dmaengine_result that is passed in to callback_result has two fields: + + result: This provides the transfer result defined by + dmaengine_tx_result. Either success or some error + condition. + + residue: Provides the residue bytes of the transfer for those that + support residue. * device_issue_pending - Takes the first transaction descriptor in the pending queue, -- cgit