linux-kernel - Re: [PATCH 1/3] dt-bindings: spi: Update clocks property for ARM pl022

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Message-ID: <6e14bdd4-5924-dd58-41ef-5bdb5561913b@arm.com>
Date:   Mon, 28 Feb 2022 14:26:12 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Kuldeep Singh <singh.kuldeep87k@...il.com>,
        Mark Brown <broonie@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 1/3] dt-bindings: spi: Update clocks property for ARM
 pl022

On 2022-02-28 12:43, Kuldeep Singh wrote:
> Add missing minItems property to clocks in ARM pl022 bindings.
> 
> This also helps in resolving below dtc warnings:
> arch/arm64/boot/dts/amd/amd-overdrive.dt.yaml: spi@...20000: clocks: [[4]] is too short
>      From schema: Documentation/devicetree/bindings/spi/spi-pl022.yaml
> arch/arm64/boot/dts/amd/amd-overdrive.dt.yaml: spi@...20000: clock-names: ['apb_pclk'] is too short
>      From schema: Documentation/devicetree/bindings/spi/spi-pl022.yaml

Who says that minItems is missing? Looking at the PL022 TRM[1] it seems 
clear that SSPCLK is pretty fundamental to useful operation. If that DT 
ever worked, it must be that the same clock is wired to both inputs, and 
the fact that that's how the neighbouring PL011 is described is strongly 
suggestive.

If the point of schema is to find errors in DTs, doesn't it make more 
sense to fix the DTs than to weaken the schema just to shut it up?

Of course in this particular case there's also the question of whether 
the most humane way to "fix" the Seattle DTs is to simply delete them, 
but that's orthogonal.

Robin.

[1] https://developer.arm.com/documentation/ddi0194/h/?lang=en

> Signed-off-by: Kuldeep Singh <singh.kuldeep87k@...il.com>
> ---
>   Documentation/devicetree/bindings/spi/spi-pl022.yaml | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-pl022.yaml b/Documentation/devicetree/bindings/spi/spi-pl022.yaml
> index 6d633728fc2b..7d36e15db5b3 100644
> --- a/Documentation/devicetree/bindings/spi/spi-pl022.yaml
> +++ b/Documentation/devicetree/bindings/spi/spi-pl022.yaml
> @@ -34,6 +34,7 @@ properties:
>       maxItems: 1
>   
>     clocks:
> +    minItems: 1
>       maxItems: 2
>   
>     clock-names: