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SubjectRe: [PATCH] fsldma: dev_err 1 too early.
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On Wed, 2009-02-25 at 05:47 -0700, Roel Kluin wrote:
> If unsuccessful, i reaches 101 after the loop, so 100 is still success.
>
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index 70126a6..444c4e4 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -168,7 +168,7 @@ static void dma_halt(struct fsl_dma_chan *fsl_chan)
>
> while (!dma_is_idle(fsl_chan) && (i++ < 100))
> udelay(10);
> - if (i >= 100 && !dma_is_idle(fsl_chan))
> + if (i > 100 && !dma_is_idle(fsl_chan))
> dev_err(fsl_chan->dev, "DMA halt timeout!\n");
> }
>

Thanks for the report. I prefer a more canonical loop. Objections?

--
Dan

<-----
fsldma: fix off by one in dma_halt
From: Dan Williams <dan.j.williams@intel.com>

Prevent dev_err from firing even if we successfully detected 'dma-idle'
before the full 1ms timeout has elapsed.

Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dma/fsldma.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 70126a6..86d6da4 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -158,7 +158,8 @@ static void dma_start(struct fsl_dma_chan *fsl_chan)

static void dma_halt(struct fsl_dma_chan *fsl_chan)
{
- int i = 0;
+ int i;
+
DMA_OUT(fsl_chan, &fsl_chan->reg_base->mr,
DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) | FSL_DMA_MR_CA,
32);
@@ -166,8 +167,11 @@ static void dma_halt(struct fsl_dma_chan *fsl_chan)
DMA_IN(fsl_chan, &fsl_chan->reg_base->mr, 32) & ~(FSL_DMA_MR_CS
| FSL_DMA_MR_EMS_EN | FSL_DMA_MR_CA), 32);

- while (!dma_is_idle(fsl_chan) && (i++ < 100))
+ for (i = 0; i < 100; i++) {
+ if (dma_is_idle(fsl_chan))
+ break;
udelay(10);
+ }
if (i >= 100 && !dma_is_idle(fsl_chan))
dev_err(fsl_chan->dev, "DMA halt timeout!\n");
}



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