Commit 1caa589d authored Aug 05, 2014 by Laura Abbott Committed by Liam Mark Jul 07, 2017

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 cce818da

include/linux/dma-mapping.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,11 @@
		*/
		#define DMA_ATTR_PRIVILEGED (1UL << 9)

		/*
		* DMA_ATTR_SKIP_ZEROING: Do not zero mapping.
		*/
		#define DMA_ATTR_SKIP_ZEROING (1UL << 10)

		/*
		* A dma_addr_t can hold any valid DMA or bus address for the platform.
		* It can be given to a device to use as a DMA source or target. A CPU cannot