Re: [PATCH v2 1/2] dt-bindings: watchdog: realtek,otto-wdt: Add fallback compatible

[Rob Herring <robh@kernel.org>]

On Wed, May 13, 2026 at 05:20:59PM -0700, Guenter Roeck wrote:
> On Tue, May 12, 2026 at 10:48:53PM +0200, Sander Vanheule wrote:
> > As all known hardware instantiations of this watchdog behave the same, a
> > fallback compatible can be added.
> > 
> > To remain compatible with existing single-compatible bindings, the
> > current compatibles are duplicated. New compatibles should only be added
> > to the list with fallback.
> > 
> > Signed-off-by: Sander Vanheule <sander@svanheule.net>
> > ---
> > Changes since v1:
> > - Fix indendations
> > - Add deprecated property to old compatible
> > - Use two-part compatible in example
> > ---
> >  .../bindings/watchdog/realtek,otto-wdt.yaml   | 22 ++++++++++++++-----
> >  1 file changed, 16 insertions(+), 6 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> > index 1f5390a67cdb..e470e0fcbb2a 100644
> > --- a/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> > +++ b/Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
> > @@ -25,11 +25,21 @@ allOf:
> >  
> >  properties:
> >    compatible:
> > -    enum:
> > -      - realtek,rtl8380-wdt
> > -      - realtek,rtl8390-wdt
> > -      - realtek,rtl9300-wdt
> > -      - realtek,rtl9310-wdt
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - realtek,rtl8380-wdt
> > +              - realtek,rtl8390-wdt
> > +              - realtek,rtl9300-wdt
> > +              - realtek,rtl9310-wdt
> > +          - const: realtek,otto-wdt
> 
> For the Apple watchdog driver, the generic property "apple,wdt" is
> considered to be bad and is not supposed to be used for newer chips.
> For this watchdog driver, a generic property is introduced.
> 
> What is the overall logic ? Is there some rule when a generic property
> such as "realtek,otto-wdt" is appropriate and preferred, and when it isn't
> (as in "apple,wdt") ?

Never preferred. Retroactively adding them, that's a definite no.

Rob