[PATCH V3 1/2] of: Add generic device tree DMA helpers

[Mark Brown]

On Thu, May 17, 2012 at 02:22:23PM +0100, Russell King - ARM Linux wrote:

> DMA on the other hand seems to have cases where you can make a choice
> between two or more providers of the service.  The impression that I'm
> getting from this thread is that it's difficult to describe that kind
> of relationship in DT - DT is good at describing "A provides X to C"
> but not "A _or_ B provides X to C and you can chose either A or B
> depending on <something> to satisfy X".

A similar thing exists in a lot of clock trees - often the final clock
block before an IP block includes a mux which could come from one of a
number of sources.