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From:   Javier Martinez Canillas <javier@dowhile0.org>
Date:   Tue, 27 Dec 2022 23:16:46 +0100
Message-ID: <CABxcv=mFzuUq0-PQ8H3N0Sxmzg+z1v_uwhUe0jcH2++NDQRR0w@mail.gmail.com>
Subject: Re: [PATCH v3 1/4] dt-bindings: display: Add Himax HX8394 panel controller
To:     Jagan Teki <jagan@amarulasolutions.com>
Cc:     Javier Martinez Canillas <javierm@redhat.com>,
        devicetree@vger.kernel.org, Robert Mader <robert.mader@posteo.de>,
        Onuralp Sezer <thunderbirdtr@fedoraproject.org>,
        Neal Gompa <ngompa13@gmail.com>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Tom Fitzhenry <tom@tom-fitzhenry.me.uk>,
        Martijn Braam <martijn@brixit.nl>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Ondrej Jirman <megi@xff.cz>,
        Peter Robinson <pbrobinson@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        =?UTF-8?Q?Kamil_Trzci=C5=84ski?= <ayufan@ayufan.eu>,
        Thierry Reding <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Maya Matuszczyk <maccraft123mc@gmail.com>
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On Tue, Dec 27, 2022 at 8:37 PM Jagan Teki <jagan@amarulasolutions.com> wrote:
>
> On Wed, Dec 28, 2022 at 12:58 AM Javier Martinez Canillas
> <javier@dowhile0.org> wrote:
> >
> > Hello Jagan,
> >
> > On Tue, Dec 27, 2022 at 7:16 PM Jagan Teki <jagan@amarulasolutions.com> wrote:
> >
> > [...]
> >
> > > > +allOf:
> > > > +  - $ref: panel-common.yaml#
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    enum:
> > > > +      # HannStar HSD060BHW4 5.99" 720x1440 TFT LCD panel
> > > > +      - hannstar,hsd060bhw4
> > >
> > > Parent controller can have a compatible where the associated panels
> > > will be enum list.
> > >
> >
> > I'm not sure to follow what you meant. Could you please elaborate?
>
> compatible:
>     items:
>       - enum:
>           - hannstar,hsd060bhw4
>       - const: himax,hx8394
>
> himax,hx8394 is the actual controller and is denoted as fallback compatible.
>

I see. Do you have an example of a panel controller that does this? I
don't see that much value in doing this since you want the DTS to
describe the actual HW and so want the panel I believe.

But also there isn't an of_device_id entry for this fallback
controller compatible string. Feel free to propose that as a follow-up
if you think it is worth doing so.

Best regards,
Javier