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.