From: Vinod Koul Date: Wed, 5 Aug 2015 03:12:04 +0000 (+0530) Subject: Documentation: dmaengine: fix the DMA_CTRL_ACK documentation X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=06f10e2f936424496d44e5541c220845c8c55345;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git Documentation: dmaengine: fix the DMA_CTRL_ACK documentation As discussed recently the meaning of DMA_CTRL_ACK is that a desc cannot be reused by provider until the client acknowledges receipt, i.e. has has a chance to establish any dependency chains. So update documentation Signed-off-by: Vinod Koul Acked-by:Robert Jarzmik --- diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt index ca67b0f04c6e..243889ec5c5a 100644 --- a/Documentation/dmaengine/provider.txt +++ b/Documentation/dmaengine/provider.txt @@ -345,12 +345,12 @@ where to put them) that abstracts it away. * DMA_CTRL_ACK - - If set, the transfer can be reused after being completed. - - There is a guarantee the transfer won't be freed until it is acked - by async_tx_ack(). - - As a consequence, if a device driver wants to skip the dma_map_sg() and - dma_unmap_sg() in between 2 transfers, because the DMA'd data wasn't used, - it can resubmit the transfer right after its completion. + - If clear, the descriptor cannot be reused by provider until the + client acknowledges receipt, i.e. has has a chance to establish any + dependency chains + - This can be acked by invoking async_tx_ack() + - If set, does not mean descriptor can be reused + General Design Notes --------------------