From 2e4ed0879eb15230cb58c3915ac51620480375c3 Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Tue, 7 Jun 2016 11:19:44 +0300 Subject: [PATCH] dmaengine: edma: Use early completion for intermediate paRAM set in slave_sg The driver limits the physical number of paRAM slots to be used by channels. If the transfer needs more slots (more SGs) then the transfer is broken up to smaller chunks. When the chunk is finished the driver will rewrite the physical slots and continues the transfer. This set up time can take some time and we might miss DMA events. If the intermediate set completion is using early completion (the interrupt will happen when the last slot is issued to the TPTC and not when the transfer is finished by the TPTC) we will have a bit more time to update the paRAM slots and less likely to have missed events. Signed-off-by: Peter Ujfalusi Signed-off-by: Vinod Koul --- drivers/dma/edma.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 8181ed131386..7c76b558cf82 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -1114,14 +1114,17 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg( edesc->absync = ret; edesc->residue += sg_dma_len(sg); - /* If this is the last in a current SG set of transactions, - enable interrupts so that next set is processed */ - if (!((i+1) % MAX_NR_SG)) - edesc->pset[i].param.opt |= TCINTEN; - - /* If this is the last set, enable completion interrupt flag */ if (i == sg_len - 1) + /* Enable completion interrupt */ edesc->pset[i].param.opt |= TCINTEN; + else if (!((i+1) % MAX_NR_SG)) + /* + * Enable early completion interrupt for the + * intermediateset. In this case the driver will be + * notified when the paRAM set is submitted to TC. This + * will allow more time to set up the next set of slots. + */ + edesc->pset[i].param.opt |= (TCINTEN | TCCMODE); } edesc->residue_stat = edesc->residue;