Messages in this thread | | | Date | Thu, 5 Jan 2012 09:56:10 +0800 | From | Richard Zhao <> | Subject | Re: [PATCH v2 2/2] dma/imx-sdma: add wmb before enable a channel |
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Hi Sascha,
On Wed, Jan 04, 2012 at 10:31:58AM +0800, Richard Zhao wrote: > On Tue, Jan 03, 2012 at 05:46:39PM +0000, Russell King - ARM Linux wrote: > > 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); }) > Why does writel always call wmb? ioremap memory needs mb too? > Isn't it supposed to be when there's prior touch of dma memory? What do you think?
Thanks Richard > > Thanks > Richard > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
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