From a3ee0bf23eaec2ae46fc6b1266bdaa5995b55c1e Mon Sep 17 00:00:00 2001 From: Michael Hennerich Date: Thu, 16 May 2019 12:44:30 +0300 Subject: [PATCH] dmaengine: axi-dmac: Enable TLAST handling The TLAST flag is used by the DMAC HDL controller to signal to the controller that the following segment (to be submitted) is the last one (in a series of segments). A receiver DMA (typically another DMAC) can read this parameter (from the transfer), and terminate the transfer earlier. A typical use-case for this, is when the receiver expects a certain amount of segments, but for some reason (e.g. an ADC capture which can have an unknown number of digital samples) the number of actual segments is smaller. The receiver would read this flag, and then the DMAC would finish. Signed-off-by: Michael Hennerich Signed-off-by: Alexandru Ardelean Signed-off-by: Vinod Koul --- drivers/dma/dma-axi-dmac.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c index 4d2cae0bebb5..8e64b81c2d3c 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -71,6 +71,7 @@ #define AXI_DMAC_IRQ_EOT BIT(1) #define AXI_DMAC_FLAG_CYCLIC BIT(0) +#define AXI_DMAC_FLAG_LAST BIT(1) /* The maximum ID allocated by the hardware is 31 */ #define AXI_DMAC_SG_UNUSED 32U @@ -216,6 +217,7 @@ static void axi_dmac_start_transfer(struct axi_dmac_chan *chan) desc->num_submitted = 0; /* Start again */ else chan->next_desc = NULL; + flags |= AXI_DMAC_FLAG_LAST; } else { chan->next_desc = desc; }