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From:   Lucas Tanure <tanure@linux.com>
Date:   Wed, 21 Jun 2023 08:37:02 +0100
Message-ID: <CAJX_Q+3im20qphOXzn-=58Kx4--ajbaF4P8BVvRcDcPXn1Qheg@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] arm64: dts: meson-t7-a311d2-khadas-vim4: add
 initial device-tree
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     Yixun Lan <dlan@gentoo.org>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Kevin Hilman <khilman@baylibre.com>, Nick <nick@khadas.com>,
        Artem <art@khadas.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
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On Wed, Jun 21, 2023 at 7:02 AM Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 21/06/2023 00:09, Yixun Lan wrote:
> >> +            apb4: bus@fe000000 {
> >> +                    compatible = "simple-bus";
> >> +                    reg = <0x0 0xfe000000 0x0 0x480000>;
> >> +                    #address-cells = <2>;
> >> +                    #size-cells = <2>;
> >> +                    ranges = <0x0 0x0 0x0 0xfe000000 0x0 0x480000>;
> >> +
> >> +                    uart_A: serial@78000 {
> >> +                            compatible = "amlogic,meson-t7-uart",
> >                                               ~~~~~~~~~~~~~~~~~
> > if you introduce new compatible string, then at least you need to document it
> > so Documentation/devicetree/bindings/serial/amlogic,meson-uart.yaml need to be updated
> >
> > but my qeustion here, why bother introducing new compatible string if nothing
> > changed with the compatible data? given the uart is same IP with g12a, can't we just
> > use "amlogic,meson-g12-uart" for this? no only it will reduce the structure length of
> > meson_uart_dt_match[], but also relieve maintainer's review burden?
>
> https://elixir.bootlin.com/linux/v6.1-rc1/source/Documentation/devicetree/bindings/writing-bindings.rst#L42
>
> Best regards,
> Krzysztof
>
Hi, I did not understand the recommendation here.
Can I add "amlogic,meson-t7-uart" without Documentation changes?
I think Yes, as I can see a few compatible strings in dts that don't
exist anywhere else.

My idea here is to add "amlogic,meson-t7-uart" for future use if ever
created, like if we find a bug in the future that is only relevant to
T7 soc.
But for now, fallback to s4 uart, as it seems to be the same controller.

From Krzysztof said in the writing-bindings.rst, I am following the rules.

So, what's the path forward here?

Thanks
Lucas