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>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index 5f3492e5d28f..a2267f9ab568 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -618,6 +618,7 @@ static int __init mxs_dma_probe(struct platform_device *pdev)
 
                 mxs_chan->mxs_dma = mxs_dma;
                 mxs_chan->chan.device = &mxs_dma->dma_device;
+                dma_cookie_init(&mxs_chan->chan);
 
                 tasklet_init(&mxs_chan->tasklet, mxs_dma_tasklet,
                              (unsigned long) mxs_chan);