[PATCH V3] dma: add channel request API that supports deferred probe

[Dan Williams]

On Mon, Nov 25, 2013 at 1:47 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> From: Stephen Warren <swarren at nvidia.com>
>
> dma_request_slave_channel() simply returns NULL whenever DMA channel
> lookup fails. Lookup could fail for two distinct reasons:
>
> a) No DMA specification exists for the channel name.
>    This includes situations where no DMA specifications exist at all, or
>    other general lookup problems.
>
> b) A DMA specification does exist, yet the driver for that channel is not
>    yet registered.
>
> Case (b) should trigger deferred probe in client drivers. However, since
> they have no way to differentiate the two situations, it cannot.
>
> Implement new function dma_request_slave_channel_or_err(), which performs

Oops, one more s/_or_err/_reason/

Other than that:
Acked-by: Dan Williams <dan.j.williams at intel.com>