Re: [PATCH 10/10] hw/arm/virt: Fix devicetree warnings about the virtio-iommu node

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Wed, Aug 24, 2022 at 08:51:18PM +0100, Peter Maydell wrote:
> On Wed, 24 Aug 2022 at 16:51, Jean-Philippe Brucker
> <jean-philippe@linaro.org> wrote:
> >
> > dt-validate and dtc throw a few warnings when parsing the virtio-iommu
> > node:
> >
> >   pcie@10000000: virtio_iommu@16:compatible: ['virtio,pci-iommu'] does not contain items matching the given schema
> >   pcie@10000000: Unevaluated properties are not allowed (... 'virtio_iommu@16' were unexpected)
> >   From schema: linux/Documentation/devicetree/bindings/pci/host-generic-pci.yaml
> >   pcie@10000000: virtio_iommu@16:compatible: ['virtio,pci-iommu'] does not contain items matching the given schema
> >   From schema: dtschema/schemas/pci/pci-bus.yaml
> >
> >   Warning (pci_device_reg): /pcie@10000000/virtio_iommu@16: PCI unit address format error, expected "2,0"
> >
> > The compatible property for a PCI child node should follow the rules
> > from "PCI Bus Binding to: IEEE Std 1275-1994". It should contain the
> > Vendor ID and Device ID (or class code).
> >
> > The unit-name should be "device,function".
> >
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > ---
> > Note that this doesn't follow
> > linux/Documentation/devicetree/bindings/virtio/iommu.txt, I'll update
> > that document when converting it to yaml, hopefully this Linux cycle.
> > The "virtio,pci-iommu" compatible string is not actually used by any
> > driver and only QEMU implements it, so we can get rid of it.
> 
> I'm not sure you can just change the compat string like that,
> unless you can guarantee that nobody anywhere has ever
> looked for it in a dtb. Also, "virtio,pci-iommu" is much
> clearer than "pci1af4,1057"...

I'm pretty sure nobody ever looked for it, but can't guarantee it. And yes
the PCI notation is hideous but that's what the standard requires. So I
think changing this to 'compatible = "virtio,pci-iommu", "pci1af4,1057"'
would be better.

Thanks,
Jean