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Date: Sun, 1 Jan 2012 08:14:25 +0100 From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de> To: Richard Zhao <richard.zhao@...aro.org> Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de, shawn.guo@...aro.org, vinod.koul@...el.com, dan.j.williams@...el.com, eric.miao@...aro.org, patches@...aro.org Subject: Re: [PATCH] dma/imx-sdma: add wmb before enable/run a channel Hello Richard, On Sun, Jan 01, 2012 at 11:27:40AM +0800, Richard Zhao wrote: > dma_alloc_coherent memory may be bufferable. We need to add > nececcary memory barrier. necessary > > Signed-off-by: Richard Zhao <richard.zhao@...aro.org> > --- > drivers/dma/imx-sdma.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c > index 2ebb2bc..8cd9492 100644 > --- a/drivers/dma/imx-sdma.c > +++ b/drivers/dma/imx-sdma.c > @@ -403,6 +403,7 @@ static int sdma_run_channel(struct sdma_channel *sdmac) > > init_completion(&sdmac->done); > > + wmb(); > __raw_writel(1 << channel, sdma->regs + SDMA_H_START); > > ret = wait_for_completion_timeout(&sdmac->done, HZ); > @@ -809,6 +810,7 @@ out: > > static void sdma_enable_channel(struct sdma_engine *sdma, int channel) > { > + wmb(); > __raw_writel(1 << channel, sdma->regs + SDMA_H_START); > } I don't know the sdma code very well, but wouldn't it be nice to call sdma_enable_channel() in sdma_run_channel() instead of open coding it? As you probably need some rearrangements to have sdma_enable_channel() declared in sdma_run_channel() this might be better done with a seperate patch. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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