Re: [PATCH] devicetree: Add generic IOMMU device tree bindings

[Thierry Reding <thierry.reding@gmail.com>]

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On Sat, May 17, 2014 at 05:04:55PM +0900, Cho KyongHo wrote:
> On Fri, 16 May 2014 14:23:18 +0200, Thierry Reding wrote:
[...]
> > +Examples:
> > +=========
> > +
> > +Single-master IOMMU:
> > +--------------------
> > +
> > +	iommu {
> > +		#iommu-cells = <0>;
> > +	};
> > +
> > +	master {
> > +		iommu = <&/iommu>;
> > +	};
> > +
> 
> Great work, Thierry.
> 
> One simple comment.
> 
> This should be also applicable to multi-master IOMMUs that the masters
> of an IOMMU is not configurable with ID or something.
> I think the title needs to be changed to cover such IOMMUs which always
> translate master's transactions and unable to change the configuration
> of the relationship between the masters and IOMMUs by S/W.

Agreed, how about we add a separate example for that case:

Multiple-master IOMMU with fixed associations:
----------------------------------------------

	/* multiple-master IOMMU */
	iommu {
		/*
		 * Masters are statically associated with this IOMMU and
		 * address translation is always enabled.
		 */
		#iommu-cells = <0>;
	};

	/* static association with IOMMU */
	master@1 {
		reg = <1>;
		iommus = <&/iommu>;
	};

	/* static association with IOMMU */
	master@2 {
		reg = <2>;
		iommus = <&/iommu>;
	};

?

Thierry

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