[PATCH V6 1/2] of: Add generic device tree DMA helpers

On Fri, Sep 14, 2012 at 05:41:56PM -0500, Jon Hunter wrote:

3. Supporting legacy devices not using DMA Engine

   These devices present a problem, as there may not be a uniform way to easily
   support them with regard to device tree. Ideally, these should be migrated
   to DMA engine. However, if this is not possible, then they should still be
   able to use this binding, the only constaint imposed by this implementation
   is that when requesting a DMA channel via of_dma_request_slave_channel(), it
   will return a type of dma_chan.

As far as devices not using DMA engine, the answer is we don't support
their specification in the DT model.  Note that the legacy OMAP DMA
API is scheduled for removal next year, so it's not going to be around
that much longer.