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

Thierry Reding
2014-05-17T20:48:06Z

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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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