Re: [PATCH] documentation: iommu: add description of ARM System MMU binding

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

On Mon, May 13, 2013 at 10:07:24AM +0100, Andreas Herrmann wrote:
> On Tue, May 07, 2013 at 04:26:02PM -0400, Olav Haugan wrote:
> > I think you misunderstood me. I am talking about having for example 1
> > master with two (2) context banks so that StreamID "1" goes to CB0 and
> > StreamID "2" goes to CB1. This means that the master device is attached
> > to two different domains. How do I model this with the the device tree
> > bindings?
> 
> Hi Olav,
> 
> I think with the proposed device tree binding you can't model this.
> 
> Do we have such use cases already? Or what future use cases would
> require this?
> 
> I can imagine of multiple contexts per device for stuff similar to
> what PASID in PCI Express are used for.
> 
> But in such a case you probably want to have some configurable bits in
> the StreamID (that should be set by an SMMU driver). And the DT
> binding should contain the number of contexts that a master device can
> support.

See my reply to your other thread, but I don't think this should be solved
in the SMMU driver. I really think that the device/domain configuration
should be driven by the master device drivers, rather than the device-tree.

Will