[PATCH 1/8] ARM: OMAP: fix DMA vs memory ordering

[Felipe Balbi]

On Wed, Apr 18, 2012 at 11:10:35AM +0100, Russell King wrote:
> Using coherent DMA memory with the OMAP DMA engine results in
> unpredictable behaviour due to memory ordering issues; as things stand,
> there is no guarantee that data written to coherent DMA memory will be
> visible to the DMA hardware.
> 
> This is because the OMAP dma_write() accessor contains no barriers,
> necessary on ARMv6 and above.  The effect of this can be seen in comments
> in the OMAP serial driver, which incorrectly talks about cache flushing
> for the coherent DMA stuff.
> 
> Rather than adding barriers to the accessors, add it in the DMA support
> code just before we enable DMA, and just after we disable DMA.  This
> avoids having barriers for every DMA register access.
> 
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>

cool, should this go to stable too ?

-- 
balbi
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