Re: [PATCH 10/54] dt-bindings: display: panel-lvds: Document panel compatibles

Rob Herring
2021-08-18T13:51:18Z

On Wed, Aug 18, 2021 at 7:43 AM Maxime Ripard <maxime@cerno.tech> wrote:
>
> Hi Rob, Sam,
>
> On Wed, Jul 21, 2021 at 08:29:47PM -0600, Rob Herring wrote:
> > On Wed, Jul 21, 2021 at 04:03:40PM +0200, Maxime Ripard wrote:
> > > The binding mentions that all the drivers using that driver must use a
> > > vendor-specific compatible but never enforces it, nor documents the
> > > vendor-specific compatibles.
> > >
> > > Let's make we document all of them, and that the binding will create an
> > > error if we add one that isn't.
> > >
> > > Cc: dri-devel@lists.freedesktop.org
> > > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > Cc: Sam Ravnborg <sam@ravnborg.org>
> > > Cc: Thierry Reding <thierry.reding@gmail.com>
> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > > ---
> > > .../bindings/display/panel/lvds.yaml | 18 ++++++++++++------
> > > 1 file changed, 12 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/panel/lvds.yaml b/Documentation/devicetree/bindings/display/panel/lvds.yaml
> > > index 49460c9dceea..d1513111eb48 100644
> > > --- a/Documentation/devicetree/bindings/display/panel/lvds.yaml
> > > +++ b/Documentation/devicetree/bindings/display/panel/lvds.yaml
> > > @@ -31,12 +31,18 @@ allOf:
> > >
> > > properties:
> > > compatible:
> > > - contains:
> > > - const: panel-lvds
> > > - description:
> > > - Shall contain "panel-lvds" in addition to a mandatory panel-specific
> > > - compatible string defined in individual panel bindings. The "panel-lvds"
> > > - value shall never be used on its own.
> > > + items:
> > > + - enum:
> > > + - advantech,idk-1110wr
> >
> > At least this one is documented elsewhere.
>
> Indeed, I missed it.
>
> > You can add 'minItems: 2' if you want to just enforce having 2 compatibles. Or do:
> >
> > items:
> > - {}
> > - const: panel-lvds
> >
> > Which also enforces the order.
>
> It's not just about the order since a missing compatible will also raise
> a warning.
>
> Some of those panels have a binding of their own, but some probably
> won't (and I can't find anything specific about the one I'm most
> interested in: tbs,a711-panel)
>
> Can we have something like:
>
> compatible:
> oneOf:
> - items:
> - enum:
> - tbs,a711-panel
> - const: panel-lvds
>
> - items:
> - {}
> - const: panel-lvds
>
> That would work for both cases I guess?

No, both conditions will be true. If you use 'anyOf', then we're never
really checking the specific compatible.

I think the problem here is trying to mix a common binding (aka an
incomplete collection of properties) and a specific binding. The
former is characterized with 'additionalProperties: true' as we have
here. You need to create a 'panel-simple-lvds.yaml' schema file that
references this one, defines all the 'simple' compatibles, and sets
'unevaluatedProperties: false'.

Rob