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From:   Jagan Teki <jagan@amarulasolutions.com>
Date:   Thu, 29 Dec 2022 15:23:48 +0530
Message-ID: <CAMty3ZDJEx6J6xtbAVyO61vSKeW_7F-xWk5yvkwKvHNc1oyykA@mail.gmail.com>
Subject: Re: [PATCH v3 1/4] dt-bindings: display: Add Himax HX8394 panel controller
To:     Javier Martinez Canillas <javier@dowhile0.org>
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 Wed, Dec 28, 2022 at 3:46 AM Javier Martinez Canillas
<javier@dowhile0.org> wrote:
>
> 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.

Yes, but the Panel needs to be built on top of the display IC so the
actual parent here is the display IC and the panel is sub-HW.  This is
what usually follows, here are some reference bindings.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/display/panel/jadard,jd9365da-h3.yaml
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/display/panel/ilitek,ili9163.yaml
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/display/panel/ilitek,ili9322.yaml

Jagan.