Re: [PATCH mmc-next v3 1/2] dt-bindings: mmc: add alias example

[Ulf Hansson]

On Mon, 31 Aug 2020 at 09:58, Matthias Schiffer
<matthias.schiffer@xxxxxxxxxxxxxxx> wrote:
>
> On Fri, 2020-08-28 at 16:24 -0600, Rob Herring wrote:
> > On Tue, Aug 25, 2020 at 03:44:40PM +0200, Matthias Schiffer wrote:
> > > As for I2C and SPI, it now is possible to reserve a fixed index for
> > > mmc/mmcblk devices.
> > >
> > > Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx
> > > >
> > > ---
> > >
> > > v3: new patch
> > >
> > >  Documentation/devicetree/bindings/mmc/mmc-controller.yaml | 8
> > > ++++++++
> > >  1 file changed, 8 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/mmc/mmc-
> > > controller.yaml b/Documentation/devicetree/bindings/mmc/mmc-
> > > controller.yaml
> > > index b96da0c7f819..22ed4a36c65d 100644
> > > --- a/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
> > > +++ b/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
> > > @@ -367,6 +367,14 @@ examples:
> > >      };
> > >
> > >    - |
> > > +    /*
> > > +     * Optionally define an alias to reserve a fixed index for the
> > > +     * mmc and mmcblk devices
> > > +     */
> > > +    aliases {
> > > +        mmc0 = &mmc3;
> > > +    };
> >
> > This will break if we improve schemas because this node is actually
> > /example-1/aliases.
> >
> > So please drop. If you want, I'd really like to have a defined set
> > (i.e.
> > a schema) of alias names. This would require deleting a bunch on
> > some
> > platforms that just made up a bunch of them.
>
> Ulf suggested that I add some kind of documentation about the new mmc
> alias support to the binding docs.
>
> As long as we don't have a proper schema for aliases, should I just add
> an explanation to the toplevel description of
> Documentation/devicetree/bindings/mmc/mmc-controller.yaml, or maybe a
> comment?

I would prefer to add an explanation in the toplevel description,
although I have no strong opinion.

This is similar to what we already do for serial devices, see
Documentation/devicetree/bindings/serial/serial.yaml.

>
>
> >
> > > +
> > >      mmc3: mmc@1c12000 {
> > >          #address-cells = <1>;
> > >          #size-cells = <0>;
> > > --
> > > 2.17.1
> > >
>

Kind regards
Uffe