Re: [PATCH v3] dt-bindings: riscv: add starfive jh7100 bindings

[Drew Fustini <drew@beagleboard.org>]

On Mon, Jul 12, 2021 at 01:24:19PM +0200, Geert Uytterhoeven wrote:
> Hi Drew,
> 
> On Fri, Jul 9, 2021 at 10:17 PM Drew Fustini <drew@beagleboard.org> wrote:
> > Add DT binding documentation for the StarFive JH7100 Soc [1] and the
> > BeagleV Starlight JH7100 board [2].
> >
> > [1] https://github.com/starfive-tech/beaglev_doc
> > [2] https://github.com/beagleboard/beaglev-starlight
> >
> > Signed-off-by: Drew Fustini <drew@beagleboard.org>
> > ---
> > v3 changes:
> > - added revision number for the board and soc after question from Palmer
> 
> Thanks for the update!
> 
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/riscv/starfive.yaml
> > @@ -0,0 +1,27 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/riscv/starfive.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: StarFive SoC-based boards
> > +
> > +maintainers:
> > +  - Michael Zhu <michael.zhu@starfivetech.com>
> > +  - Drew Fustini <drew@beagleboard.org>
> > +
> > +description:
> > +  StarFive SoC-based boards
> > +
> > +properties:
> > +  $nodename:
> > +    const: '/'
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - const: beagle,beaglev-starlight-jh7100-r0
> > +          - const: starfive,jh7100-r0
> 
> While I can be convinced about the board revision number (probably you
> know better if there will be different board revisions that matter),
> I'm wondering if the revision number makes sense for the SoC part.
> Will there be a new revision of jh7100, or will the next revision
> be jh7110, which will use a different compatible value anyway?
> Is there an on-chip register that allows the kernel to find out the
> revision info? Might be better to use that with soc_device_register()
> and soc_device_match()

We do anticipate making additional BeagleV Starlight boards with the
JH7100 SoC and those new boards may need to have a different USB hub
chip due to sourcing. Thus it is possible that there will be a r1 board
in the future.

However, I think you are correct about the SoC. There won't be any new
revisions of the JH7100 SoC. All chips with that part number will have
the same design. There will eventually be JH7110 which is a different
design but I did not want to prematurely add a compatible for that.


Thanks,
Drew