Re: [PATCH v2 3/3] riscv: dts: sophgo: add zfh for sg2042

[Johan Hovold <johan@kernel.org>]

On Fri, May 16, 2025 at 05:00:50PM +0200, Alejandro Enrique wrote:
> On Fri, May 16, 2025 at 4:01 PM Conor Dooley <conor@kernel.org> wrote:
> >
> > On Fri, May 16, 2025 at 12:23:35PM +0200, Alejandro Enrique wrote:
> > > On Thu, May 15, 2025 at 5:02 PM Conor Dooley <conor@kernel.org> wrote:
> > > >
> > > > On Wed, May 14, 2025 at 06:53:25PM +0200, Alejandro Enrique wrote:
> > > > > On Wed, May 14, 2025 at 5:49 PM Conor Dooley <conor@kernel.org> wrote:
> > > > >
> > > > > > On Wed, May 14, 2025 at 01:55:54PM +0200, Alejandro Enrique via B4 Relay
> > > > > > wrote:
> > > > > > > From: Alejandro Enrique <alejandroe1@geotab.com>
> > > > > > >
> > > > > > > Add compatible for u-blox NEO-9M GPS module.
> > > > > > >
> > > > > > > Signed-off-by: Alejandro Enrique <alejandroe1@geotab.com>
> > > > > > > ---
> > > > > > >  Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 1 +
> > > > > > >  1 file changed, 1 insertion(+)
> > > > > > >
> > > > > > > diff --git a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> > > > > > b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> > > > > > > index
> > > > > > 7d4b6d49e5eea2201ac05ba6d54b1c1721172f26..cf5ff051b9ab03e5bfed8156a72170965929bb7e
> > > > > > 100644
> > > > > > > --- a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> > > > > > > +++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> > > > > > > @@ -22,6 +22,7 @@ properties:
> > > > > > >        - u-blox,neo-6m
> > > > > > >        - u-blox,neo-8
> > > > > > >        - u-blox,neo-m8
> > > > > > > +      - u-blox,neo-m9
> > > > > >
> > > > > > No match data in the driver, why is a fallback not sufficient?
> > > > > >
> > > > >
> > > > > I added the match data in the driver in the PATCH 2/2 of this series
> > > > > in the same fashion as previously supported modules.
> > > >
> > > > Did you? When I looked, there was just a compatible and no match data.
> > >
> > > You are right. I just added a compatible string, no match data. Sorry,
> > > I was not following.
> > > I just added the neo-m9 compatible the same way the neo-6m was previously
> > > added.
> > >
> > > What do you mean by using a fallback? Using one of the existent
> > > compatibles (none have match data) or adding a new fallback
> > > compatible, something like just "u-blox,neo"?
> >
> > Falling back to one of the existing ones, like neo-m8.
> 
> That is perfectly possible. I added the new compatible string based
> on what was previously done for the neo-6m one.
> https://lore.kernel.org/lkml/20190401115616.21337-5-megous@megous.com/
> 
> If that is not a good approach I think this series can be discarded already.

We still want a new compatible string for the new device. Depending on
how similar these products are it may be possible to avoid adding a new
entry to the driver for now by specifying a fallback compatible, for
example, to neo-m8:

	compatible = "u-blox,neo-m9", "u-blox,neo-m8";

This would then need to be encoded in the binding.

Johan