Re: [PATCH 2/3] Docs: dt: Add PCI MSI map bindings

[Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>]

> > +Example (5)
> > +===========
> > +
> > +/ {
> > +	#address-cells = <1>;
> > +	#size-cells = <1>;
> > +
> > +	msi_a: msi-controller@a {
> > +		reg = <0xa 0x1>;
> > +		compatible = "vendor,some-controller";
> > +		msi-controller;
> > +		#msi-cells = <1>;
> > +	};
> > +
> > +	msi_b: msi-controller@b {
> > +		reg = <0xb 0x1>;
> > +		compatible = "vendor,some-controller";
> > +		msi-controller;
> > +		#msi-cells = <1>;
> > +	};
> > +
> > +	msi_c: msi-controller@c {
> > +		reg = <0xc 0x1>;
> > +		compatible = "vendor,some-controller";
> > +		msi-controller;
> > +		#msi-cells = <1>;
> > +	};
> > +
> > +	pci: pci@c {
> > +		reg = <0xf 0x1>;
> > +		compatible = "vendor,pcie-root-complex";
> > +		device_type = "pci";
> > +
> > +		/*
> > +		 * The sideband data provided to MSI controller a is the
> > +		 * RID, but the high bit of the bus number is negated.
> > +		 * The sideband data provided to MSI controller b is the
> > +		 * RID, identity-mapped.
> > +		 * MSI controller c is not addressable.
> > +		 */
> > +		msi-map = <0x0000 &msi_a 0x8000 0x08000>,
> > +			  <0x8000 &msi_a 0x0000 0x08000>,
> > +			  <0x0000 &msi_b 0x0000 0x10000>;
> > +	};
> 
> they can be identical right? like
> 	<0x8000 &msi_a 0x0000 0x08000>,
>  	<0x8000 &msi_b 0x0000 0x08000>;

In general that would be valid, yes.

In this case two entries are required for MSI controller a because the
high bit passed to it is negated. This does not occur for MSI controller
b, so it only requires a single entry to describe the transformation.

Thanks,
Mark.
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