Commit 91e4dc43 authored Aug 05, 2014 by Laura Abbott Committed by Patrick Daly Aug 24, 2016

arm: Add option to skip buffer zeroing



The DMA framework currently zeros all buffers because it (righfully so)
assumes that drivers will soon need to pass the memory to a device.
Some devices/use case may not require zeroed memory and there can
be an increase in performance if we skip the zeroing. Add a DMA_ATTR
to allow skipping of DMA zeroing.

Change-Id: Id9ccab355554b3163d8e7eae1caa82460e171e34
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>

parent 7901b943

include/linux/dma-mapping.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -62,6 +62,10 @@
		* No speculative access may occur in this mapping.
		*/
		#define DMA_ATTR_STRONGLY_ORDERED (1UL << 8)
		/*
		* DMA_ATTR_SKIP_ZEROING: Do not zero mapping.
		*/
		#define DMA_ATTR_SKIP_ZEROING (1UL << 9)

		/*
		* A dma_addr_t can hold any valid DMA or bus address for the platform.