Re: [PATCH RFC 08/12] dt-bindings: remoteproc: add remoteproc-virtio

[Rob Herring <robh@kernel.org>]

On Tue, Sep 22, 2026 at 09:44:20PM +0200, Francesco Valla wrote:
> On Tue, Sep 22, 2026 at 09:40:31AM -0600, Mathieu Poirier wrote:
> > On Wed, Sep 16, 2026 at 11:10:53PM +0200, Francesco Valla wrote:
> > > Add a new binding to describe remoteproc-provided virtio devices; while
> > > these are discovered through a resource table parsed by the remoteproc
> > > infrastructure at runtime, their description can be needed to probe
> > > non-discoverable buses (such as I2C) or to link consumers and suppliers.
> > > 
> > > Each vdev is described by a dedicated "group" node, which then includes
> > > a virtio-device node, which binding is already existent and used by
> > > virtio-mmio. Each vdev shall be stattically linked to a "group" node
> > > using its index inside the resource table as the reg property of the
> > > node; this permits to have multiple instances of the same type of
> > > device.
> > > 
> > > The binding is intended to be generic and adopted by any remoteproc
> > > provider.
> > > 
> > > Signed-off-by: Francesco Valla <francesco@valla.it>
> > > ---
> > >  .../bindings/remoteproc/remoteproc-virtio.yaml     | 89 ++++++++++++++++++++++
> > >  1 file changed, 89 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml b/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml
> > > new file mode 100644
> > > index 000000000000..c4a0d84b1460
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/remoteproc/remoteproc-virtio.yaml
> > > @@ -0,0 +1,89 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/remoteproc/remoteproc-virtio.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Virtio devices over remoteproc
> > > +
> > > +description: |
> > > +  Virtio devices ("vdevs") can be exposed using the remoteproc infrastructure
> > > +  and its resource table. For some of them, a device tree node might be needed
> > > +  to describe remote undiscoverable hardware and/or connect consumers and
> > > +  providers.
> > > +
> > > +maintainers:
> > > +  - Francesco Valla <francesco@valla.it>
> > > +
> > > +properties:
> > > +  virtio:
> > > +    description: Contains a group of Virtio devices exposed by the remoteproc.
> > > +
> > > +    properties:
> > > +      '#address-cells':
> > > +        const: 1
> > > +
> > > +      '#size-cells':
> > > +        const: 0
> > > +
> > > +    patternProperties:
> > > +      "^vdev@[0-9a-f]+$":
> > > +        type: object
> > > +
> > > +        properties:
> > > +          reg:
> > > +            description: Virtio device index inside the resource table.

Who/what defines the resource table?

> > > +            maxItems: 1
> > > +
> > > +        additionalProperties:
> > > +          type: object
> > > +          $ref: /schemas/virtio/virtio-device.yaml
> > > +          maxItems: 1
> > > +
> > > +        required:
> > > +          - reg
> > > +
> > > +    additionalProperties: false

Preferred to put this before 'properties' in the indented cases. Easier 
to see what level it belongs to.

> > > +
> > > +    required:
> > > +      - '#address-cells'
> > > +      - '#size-cells'
> > > +
> > > +additionalProperties: true
> > > +
> > > +examples:
> > > +  - |
> > > +    remoteproc-cm33 {
> > > +      virtio {
> > > +          #address-cells = <1>;
> > > +          #size-cells = <0>;
> > > +
> > > +          vdev@0 {
> > > +              reg = <0>;
> > > +
> > 
> > Do we need the 'reg' since we already have vdev@X?  I'll let the DT people
> > provide their input on this.
> >
> 
> AFAIK yes, because the rproc_get_vdev_fwnode() helpers search for indexed
> child nodes using the 'reg' property, not the node name. This I believe
> is the preferred way of doing things.

It is either both unit-address and reg or neither. It's preferred to 
have them unless you are just making up numbers.

Rob