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SubjectRe: [PATCH v2 2/2] dma/imx-sdma: add wmb before enable a channel
On Sun, Jan 01, 2012 at 10:38:12PM +0800, Richard Zhao wrote:
> dma_alloc_coherent memory may be bufferable. We need to add
> nececcary memory barrier.
>
> Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
> ---
> drivers/dma/imx-sdma.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index f8e87b5..9301bff 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -394,6 +394,7 @@ static int sdma_config_ownership(struct sdma_channel *sdmac,
>
> static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
> {
> + wmb();
> __raw_writel(1 << channel, sdma->regs + SDMA_H_START);

Use writel(). That's what it's there for:

#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
#define __iowmb() wmb()
#endif
#define writel_relaxed(v,c) ((void)__raw_writel((__force u32) \
cpu_to_le32(v),__mem_pci(c)))
#define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })

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