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Date:   Mon, 30 Oct 2023 11:43:27 -0500
From:   Rob Herring <robh@kernel.org>
To:     Jan Kiszka <jan.kiszka@siemens.com>
Cc:     Nishanth Menon <nm@ti.com>, Vignesh Raghavendra <vigneshr@ti.com>,
        Tero Kristo <kristo@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, Bao Cheng Su <baocheng.su@siemens.com>,
        Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
Subject: Re: [PATCH 5/7] dt-bindings: trivial-devices: Add IOT2050 Arduino
 SPI connector
Message-ID: <20231030164327.GA1242659-robh@kernel.org>
References: <cover.1698413678.git.jan.kiszka@siemens.com>
 <7838d99a1795337c73f480fafcbf698fc17d16dd.1698413678.git.jan.kiszka@siemens.com>
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On Fri, Oct 27, 2023 at 03:34:36PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> On the Siemens IOT2050 devices, the SPI controller wired to the Arduino
> connector is normally driven by userspace. Introduce a binding for use
> by spidev.

What's spidev? Not a h/w device...


> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
> index 430a814f64a5..01b9f36afcd5 100644
> --- a/Documentation/devicetree/bindings/trivial-devices.yaml
> +++ b/Documentation/devicetree/bindings/trivial-devices.yaml
> @@ -349,6 +349,8 @@ properties:
>            - silabs,si3210
>              # Relative Humidity and Temperature Sensors
>            - silabs,si7020
> +            # Siemens IOT2050: SPI interface on Arduino connector
> +          - siemens,iot2050-arduino-spi

How is this specific to your board? Presumably, an 'Arduino connector' 
is a somewhat standard interface, right? If every board with an Arduino 
connector adds a compatible, this doesn't scale.

A connector is what you should be describing, but I imagine it is not 
just SPI. Here's some past discussions[1][2] on the need for connector 
bindings.

Rob


[1] https://lore.kernel.org/all/20220421094421.288672-1-michael@walle.cc/
[2] https://lore.kernel.org/all/CAL_JsqK2DKPbaFvUPSU2E7oh1_pryrRXPMg8OASmK722jmznwA@mail.gmail.com/