linux-kernel - Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

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Date:   Thu, 15 Jul 2021 09:12:40 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Robin van der Gracht <robin@...tonic.nl>,
        Miguel Ojeda <ojeda@...nel.org>,
        Paul Burton <paulburton@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Pavel Machek <pavel@....cz>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-leds <linux-leds@...r.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document
 Adafruit segment displays

Hi Rob,

Note that you commented on v2, while I posted v3 yesterday.

On Wed, Jul 14, 2021 at 10:36 PM Rob Herring <robh@...nel.org> wrote:
> On Fri, Jun 25, 2021 at 02:58:46PM +0200, Geert Uytterhoeven wrote:
> > The Holtek HT16K33 LED controller is not only used for driving
> > dot-matrix displays, but also for driving segment displays.
> >
> > Document compatible values for the Adafruit 7-segment[1] and
> > 14-segment[2] FeatherWing expansion boards with red displays.  According
> > to the schematics, all other Adafruit 7-segment and 14-segment display
> > backpack and FeatherWing expansion boards (including bare boards and
> > boards fitted with displays) are compatible with these two boards.
> > Add a "color" property to support the different color variants.
> >
> > [1] https://www.adafruit.com/product/3108
> > [2] https://www.adafruit.com/product/3130
> >
> > Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>

> > --- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > +++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > @@ -14,14 +14,23 @@ allOf:
> >
> >  properties:
> >    compatible:
> > -    const: holtek,ht16k33
> > +    oneOf:
> > +      - items:
> > +          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> > +          - const: holtek,ht16k33
> > +
> > +      - items:
> > +          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> > +          - const: holtek,ht16k33
>
> These 2 entries can be combined.

Right.  This split dates back from when I considered adding all
possible compatible values.  It can indeed be simplified to:

          - enum:
              - adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing
Display (Red)
              - adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing
Display (Red)
          - const: holtek,ht16k33

> Or make the comment a 'description'.

What do you mean?

>
> > +
> > +      - const: holtek,ht16k33     # Generic 16*8 LED controller with dot-matrix display

> >  required:
> >    - compatible
> >    - reg
> > -  - refresh-rate-hz
> > +
> > +if:
> > +  properties:
> > +    compatible:
> > +      const: holtek,ht16k33
>
> Isn't this always true?

It is false if there is more than one compatible value.

>
> > +then:
> > +  required:
> > +    - refresh-rate-hz
> >
> >  additionalProperties: false

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds