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dmaengine: ensure all DMA engine drivers initialize their cookies

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Ensure all DMA engine drivers initialize their cookies in the same way,
so that they all behave in a similar fashion.  This means their first
issued cookie will be 2 rather than 1, and will increment to INT_MAX
before returning 1 and starting over.

In connection with this, Dan Williams said:
> Russell King wrote:
> > Secondly, some DMA engine drivers initialize the dma_chan cookie to 0,
> > others to 1.  Is there a reason for this, or are these all buggy?
>
> I know that ioat and iop-adma expect 0 to mean "I have cleaned up this
> descriptor and it is idle", and would break if zero was an in-flight
> cookie value.  The reserved usage of zero is an driver internal
> concern, but I have no problem formalizing it as a reserved value.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
This commit is contained in:
Russell King - ARM Linux
2012-03-06 22:36:27 +00:00
committed by Vinod Koul
parent 2a926e4602
commit 8ac695463f
9 changed files with 9 additions and 0 deletions
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drivers/dma/imx-dma.c
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@@ -347,6 +347,7 @@ static int __init imxdma_probe(struct platform_device *pdev)
spin_lock_init(&imxdmac->lock);
imxdmac->chan.device = &imxdma->dma_device;
dma_cookie_init(&imxdmac->chan);
imxdmac->channel = i;
/* Add the channel to the DMAC list */