[RFC/RFT 2/2] ARM: keystone: Install hooks for dma address translation routines

Arnd Bergmann arnd at arndb.de
Tue Feb 4 11:01:59 EST 2014

On Tuesday 04 February 2014, Santosh Shilimkar wrote:
> > PPC servers use "ibm,dma-window" to describe the assigned dma address
> > space for busses/devices, but the window itself doesn't contain any
> > information about the physical address mapping (since it goes through
> > an iommu after that). It likely doesn't fit this particular use case,
> > but it's something we should look at as a base in case we need to
> > start looking at bindings for this instead of coding it per SoC. We'll
> > know more once we've seen what a few of the implementations out there
> > are.
> > 
> Understood.

I think you are looking for the "dma-ranges" property, which describes
how a device DMA address space maps into the parent bus address space
for inbound translations. It's not used much in Linux, but it is clearly
specified. The "ibm,dma-window" property OTOH is for the corner case
that you have a small per-partition DMA address space section, which is
not how things are done on most systems these days.


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