linux-kernel - Re: [PATCH 3/4] arm64: dts: mediatek: mt8183: disable quad mode for spi nor

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Date:   Wed, 16 Aug 2023 14:17:41 +0300
From:   Eugen Hristev <eugen.hristev@...labora.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>,
        Tudor Ambarus <tudor.ambarus@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     Pratyush Yadav <pratyush@...nel.org>,
        Michael Walle <michael@...le.cc>,
        "Miquel Raynal )" <miquel.raynal@...tlin.com>,
        "Richard Weinberger )" <richard@....at>,
        "Vignesh Raghavendra )" <vigneshr@...com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        cros-qcom-dts-watchers@...omium.org,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: Re: [PATCH 3/4] arm64: dts: mediatek: mt8183: disable quad mode for
 spi nor

On 8/15/23 18:31, Hsin-Yi Wang wrote:
> Some of the SKUs are using gigadevice gd25lq64c flash chip. The chip
> default enables quad mode, which results in the write protect pin set to
> IO pin. In mt8183 kukui, we won't use quad enable for all SKUs, so apply
> the property to disable spi nor's quad mode.

Hi Hsin-Yi,

To me this property, and the way you 'apply' it, makes me think that you 
are using the devicetree as a configuration and not a description of the 
hardware itself.
I think the driver should decide whether to use quad or not depending on 
the situation or the pinout of the device (as in your case quad mode 
overlaps with the WP pin)

Eugen

> 
> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> ---
>   arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi b/arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi
> index 6ce16a265e053..8e4761e2b8ff4 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi
> @@ -877,6 +877,7 @@ w25q64dw: flash@0 {
>   		compatible = "winbond,w25q64dw", "jedec,spi-nor";
>   		reg = <0>;
>   		spi-max-frequency = <25000000>;
> +		disable-quad-mode;
>   	};
>   };
>