Re: [PATCH 5/6] dma-mapping: support fsl-mc bus

On Mon, Mar 05, 2018 at 03:48:32PM +0000, Robin Murphy wrote:

Unfortunately for us, fsl-mc is conceptually rather like PCI in that it's 
software-discoverable and the only thing described in DT is the bus "host", 
thus we need the same sort of thing as for PCI to map from the child 
devices back to the bus root in order to find the appropriate firmware 
node. Worse than PCI, though, we wouldn't even have the option of 
describing child devices statically in firmware at all, since it's actually 
one of these runtime-configurable "build your own network accelerator" 
hardware pools where userspace gets to create and destroy "devices" as it 
likes.

I really hate the PCI special case just as much.  Maybe we just
need a dma_configure method on the bus, and move PCI as well as fsl-mc
to it.