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Message-ID: <c964bf2c-f7bf-451c-1691-02903f20c634@pengutronix.de>
Date:   Mon, 28 Mar 2022 09:20:46 +0200
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From:   Ahmad Fatoum <a.fatoum@pengutronix.de>
Subject: Re: [PATCH 3/5] arm64: dts: imx8mp: Enable HS400-ES
To:     Adam Ford <aford173@gmail.com>, linux-mmc@vger.kernel.org
Cc:     devicetree@vger.kernel.org, Ulf Hansson <ulf.hansson@linaro.org>,
        Fabio Estevam <festevam@gmail.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        aford@beaconembedded.com, haibo.chen@nxp.com,
        linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        linux-arm-kernel@lists.infradead.org
References: <20220327123835.28329-1-aford173@gmail.com>
 <20220327123835.28329-3-aford173@gmail.com>
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Hello Adam,

On 27.03.22 14:38, Adam Ford wrote:
> The SDHC controller in the imx8mp has the same controller
> as the imx8mm which supports HS400-ES. Change the compatible
> fallback to imx8mm to enable it.

I believe that's a shortcoming of the Linux driver, which should explicitly list
fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it.

I find dropping compatibles problematic, because like Linux matching
fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match
fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc.

I'd prefer that either the kernel driver gains extra compatibles or that
the DTS lists extra compatibles and we refrain from dropping existing
(correct) ones.

What do you think?

Cheers,
Ahmad

> Signed-off-by: Adam Ford <aford173@gmail.com>
> ---
>  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> index 794d75173cf5..d5ee1520f1fe 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> @@ -769,7 +769,7 @@ i2c6: i2c@30ae0000 {
>  			};
>  
>  			usdhc1: mmc@30b40000 {
> -				compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc";
> +				compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc";
>  				reg = <0x30b40000 0x10000>;
>  				interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>;
>  				clocks = <&clk IMX8MP_CLK_DUMMY>,
> @@ -783,7 +783,7 @@ usdhc1: mmc@30b40000 {
>  			};
>  
>  			usdhc2: mmc@30b50000 {
> -				compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc";
> +				compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc";
>  				reg = <0x30b50000 0x10000>;
>  				interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH>;
>  				clocks = <&clk IMX8MP_CLK_DUMMY>,
> @@ -797,7 +797,7 @@ usdhc2: mmc@30b50000 {
>  			};
>  
>  			usdhc3: mmc@30b60000 {
> -				compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc";
> +				compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc";
>  				reg = <0x30b60000 0x10000>;
>  				interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>;
>  				clocks = <&clk IMX8MP_CLK_DUMMY>,


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