From 3565fe53334cd3f0d59ff5db0872de9370775a19 Mon Sep 17 00:00:00 2001 From: Kuninori Morimoto Date: Mon, 30 May 2016 00:41:48 +0000 Subject: dmaengine: rcar-dmac: use list_add() on rcar_dmac_desc_put() For each descriptor, in addition to the memory used by the descriptors structure itself, the driver allocates a list of chunks as well as a buffer for hardware descriptors. Descriptors themselves are preallocated, and allocation of the chunks and buffer is performed the first time the descriptor is used. The memory isn't freed when the transfer is completed, as the chunks and buffer will be needed again when the descriptor is reused internally, so the driver keeps the memory around. If only a few descriptors are used concurrently, the current list_add_tail() implementation will result in all preallocated descriptors being used before going back to the first one, and will thus allocate chunks and a buffer for all preallocated descriptors. Using list_add() will put the complete descriptor at the head of the list of available descriptors, so the next transfer will be more likely to reuse a descriptor that already has associated memory instead of one that has never been used before. Signed-off-by: Kuninori Morimoto Signed-off-by: Vinod Koul diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index dfb1792..433e982 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -510,7 +510,7 @@ static void rcar_dmac_desc_put(struct rcar_dmac_chan *chan, spin_lock_irqsave(&chan->lock, flags); list_splice_tail_init(&desc->chunks, &chan->desc.chunks_free); - list_add_tail(&desc->node, &chan->desc.free); + list_add(&desc->node, &chan->desc.free); spin_unlock_irqrestore(&chan->lock, flags); } -- cgit v0.10.2