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Date:   Fri, 28 Apr 2023 16:46:07 -0500
From:   Rob Herring <robh@kernel.org>
To:     Valentin Caron <valentin.caron@foss.st.com>
Cc:     Mark Brown <broonie@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Alain Volmat <alain.volmat@foss.st.com>,
        linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/7] dt-bindings: spi: stm32: add bindings regarding
 stm32h7 spi slave
Message-ID: <20230428214607.GA326858-robh@kernel.org>
References: <20230428121524.2125832-1-valentin.caron@foss.st.com>
 <20230428121524.2125832-5-valentin.caron@foss.st.com>
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On Fri, Apr 28, 2023 at 02:15:21PM +0200, Valentin Caron wrote:
> From: Alain Volmat <alain.volmat@foss.st.com>
> 
> Update the spi-stm32 binding yaml regarding to the SPI slave support.

Why? What problem are you trying to solve.

> 
> Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
> Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
> ---
>  Documentation/devicetree/bindings/spi/st,stm32-spi.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
> index c599eb359d56..1d26fa2658c5 100644
> --- a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
> +++ b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
> @@ -27,6 +27,7 @@ allOf:
>      then:
>        properties:
>          st,spi-midi-ns: false
> +        spi-slave: false
>  
>  properties:
>    "#address-cells": true
> @@ -62,6 +63,13 @@ properties:
>        - const: rx
>        - const: tx
>  
> +  cs-gpios:
> +    description:
> +      In case of spi-slave not defined, cs-gpios behave as defined in
> +      spi-controller.yaml.
> +      In case of spi-slave defined, if <0>, indicate that SS should be
> +      detected via the dedicated HW pin

I don't understand. I though cs-gpios was for master mode. You want to 
define 'cs-gpios = <0>;'? How would that be different than just omitting 
cs-gpios?

Rob