linux-kernel - Re: [PATCH 02/17] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

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Date:   Tue, 18 May 2021 16:35:16 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Robin van der Gracht <robin@...tonic.nl>
Cc:     Rob Herring <robh+dt@...nel.org>, Miguel Ojeda <ojeda@...nel.org>,
        Paul Burton <paulburton@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...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 02/17] dt-bindings: auxdisplay: ht16k33: Document Adafruit
 segment displays

Hoi Robin,

On Tue, Mar 23, 2021 at 10:12 AM robin <robin@...tonic.nl> wrote:
> On 2021-03-22 15:48, 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
> > +
> > +      - const: holtek,ht16k33     # Generic 16*8 LED controller with
> > dot-matrix display
> >
> >    reg:
> >      maxItems: 1
> >
> >    refresh-rate-hz:
> >      maxItems: 1
> > -    description: Display update interval in Hertz
> > +    description: Display update interval in Hertz for dot-matrix
> > displays
>
> The above should be included in patch 16

I disagree: bindings are independent from the driver implementation.

> >    interrupts:
> >      maxItems: 1
> > @@ -41,10 +50,17 @@ properties:
> >      default: 16
> >      description: Initial brightness level
> >
> > +  color: true
> > +    description:
> > +      Color of the display.  Use one of the LED_COLOR_ID_* prefixed
> > definitions
> > +      from the header include/dt-bindings/leds/common.h.  The default
> > is red.
> > +    minimum: 0
> > +    maximum: 9
> > +    default: 1
> > +
>
> The above should be included in patch 17

Same here.

> >  required:
> >    - compatible
> >    - reg
> > -  - refresh-rate-hz
>
> 'refresh-rate-hz' is still a required property for the dot-matrix /
> fbdev setup.

True.

> If it can no longer be listed here than maybe its nice to mention that
> it's required
> somewhere else (in it's description?).

    if:
      properties:
        compatible:
          const: holtek,ht16k33
    then:
      required:
        - refresh-rate-hz

Thanks!

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