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| author | Russell King - ARM Linux <linux@arm.linux.org.uk> | 2012-03-06 22:36:27 +0000 |
|---|---|---|
| committer | Vinod Koul <vinod.koul@linux.intel.com> | 2012-03-13 11:37:42 +0530 |
| commit | 8ac695463f37af902e953d575d3f782e32e170da (patch) | |
| tree | 787119e3e1cc3a32e4be22cbff7c03de098eed58 /drivers/dma/ppc4xx | |
| parent | 2a926e46022ad7a03e0ac167d8c2b0d88c12c5a8 (diff) | |
| download | lwn-8ac695463f37af902e953d575d3f782e32e170da.tar.gz lwn-8ac695463f37af902e953d575d3f782e32e170da.zip | |
dmaengine: ensure all DMA engine drivers initialize their cookies
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>
Diffstat (limited to 'drivers/dma/ppc4xx')
| -rw-r--r-- | drivers/dma/ppc4xx/adma.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/dma/ppc4xx/adma.c b/drivers/dma/ppc4xx/adma.c index 975206257f6e..ced98826684a 100644 --- a/drivers/dma/ppc4xx/adma.c +++ b/drivers/dma/ppc4xx/adma.c @@ -4497,6 +4497,7 @@ static int __devinit ppc440spe_adma_probe(struct platform_device *ofdev) INIT_LIST_HEAD(&chan->all_slots); chan->device = adev; chan->common.device = &adev->common; + dma_cookie_init(&chan->common); list_add_tail(&chan->common.device_node, &adev->common.channels); tasklet_init(&chan->irq_tasklet, ppc440spe_adma_tasklet, (unsigned long)chan); |