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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Fri, 20 Mar 2020 10:11:22 +0100
Message-ID: <CACRpkdbeLAyhhkx115zAV0tdC7KJ4T0UoQ2QeDwTVN+btxp=Jw@mail.gmail.com>
Subject: Re: [PATCH v2 2/5] dt-bindings: panel: add binding for Xingbangda
 XBD599 panel
To:     Icenowy Zheng <icenowy@aosc.io>,
        Jagan Teki <jagan@amarulasolutions.com>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Ondrej Jirman <megous@megous.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Maxime Ripard <mripard@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        "open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
        Sam Ravnborg <sam@ravnborg.org>
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On Fri, Mar 20, 2020 at 9:07 AM Icenowy Zheng <icenowy@aosc.io> wrote:
> =E4=BA=8E 2020=E5=B9=B43=E6=9C=8819=E6=97=A5 GMT+08:00 =E4=B8=8B=E5=8D=88=
10:14:27, Linus Walleij <linus.walleij@linaro.org> =E5=86=99=E5=88=B0:
> >On Mon, Mar 16, 2020 at 2:37 PM Icenowy Zheng <icenowy@aosc.io> wrote:

> >As noticed in the review of the driver, this display is very close to
> >himax,hx8363.
> >
> >I think the best is to determin what actual display controller it is,
> >I think it is some kind of Ilitek controller since Ilitek ili9342 is
> >clearly very similar.
>
> It's Sitronix ST7703, same as the Librem 5 panel.

Heh, I wonder how it comes that it is so similar to Ilitek.
I guess I will never understand how the silicon ecosystem works
in asia (I did read a lot of Bunnie Huang's articles and hardware
hacking book to try to understand...)

This file should be named sitronix,st7703.yaml then.

According to the code in the Librem 5:
https://source.puri.sm/Librem5/linux-next/blob/imx8-current-librem5/drivers=
/gpu/drm/panel/panel-sitronix-st7701.c
The actual name of the display is Techstar ts8550b.
And the display controller is st7701, so maybe we should
actually name it sitronix,st770x.yaml if there are some
sub-variants of st770x?

> >properties:
> >  compatible:
> >    items:
> >      - const: xingbangda,xbd599
> >      - const: ilitek,ili9342
> >
> >Possibly use oneOf and add support for the himax,hx8363
> >already while you're at it.

This should at least be:

compatible:
   items:
     - enum:
       - xingbangda,xbd599
       - himax,hx8363
       - techstar,ts8550b
     - enum:
       - sitronix,st7701
       - sitronix,st7703

So panel nodes using this panel become
compatible =3D "xingbangda,sbd599", "sitronix,st7703"
etc.

This way it is straight-forward for drivers to identify the panel
vendor and display controller.

Yours,
Linus Walleij