linux-kernel - Re: [PATCH 1/3] dt-bindings: auxdisplay: hit,hd44780: drop redundant GPIO node

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Message-ID: <CAMuHMdU-c5_Z2AMNtNH4Cc4JUrn+oKU-1CumEOAP6=5Zomcj_A@mail.gmail.com>
Date: Mon, 12 Feb 2024 09:41:50 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Linus Walleij <linus.walleij@...aro.org>, Miguel Ojeda <ojeda@...nel.org>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Robin van der Gracht <robin@...tonic.nl>, Paul Burton <paulburton@...nel.org>, 
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Ralf Schlatterbeck <rsc@...tux.com>
Subject: Re: [PATCH 1/3] dt-bindings: auxdisplay: hit,hd44780: drop redundant
 GPIO node

Hi Krzysztof,

CC Ralf

On Mon, Feb 12, 2024 at 9:34 AM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
> Examples of other nodes, like GPIO controller, are redundant and not
> really needed in device bindings.
>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

Thanks for your patch!

> --- a/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml
> +++ b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml
> @@ -99,17 +99,7 @@ examples:
>      };
>    - |
>      #include <dt-bindings/gpio/gpio.h>
> -    i2c {
> -            #address-cells = <1>;
> -            #size-cells = <0>;
>
> -            pcf8574: pcf8574@27 {
> -                    compatible = "nxp,pcf8574";
> -                    reg = <0x27>;
> -                    gpio-controller;
> -                    #gpio-cells = <2>;
> -            };
> -    };

This part was added delberately in commit c784e46c8445635a ("auxdisplay:
Add I2C gpio expander example"), to aid makers who are not DT experts.
Note that there are no other examples of this popular wiring scheme
in upstream DTS.

>      hd44780 {
>              compatible = "hit,hd44780";
>              display-height-chars = <2>;

If you do want to insist on removing the i2c GPIO expander part,
I think this node should be removed too, as it is almost identical
to the first example.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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