linux-kernel - Re: [PATCH 6/6] arm64: dts: imx8mm-kontron: Add support for reading SD

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Date:   Mon, 13 Feb 2023 19:12:23 +0100
From:   Marek Vasut <marex@...x.de>
To:     Marco Felsch <m.felsch@...gutronix.de>,
        Frieder Schrempf <frieder@...s.de>
Cc:     devicetree@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Heiko Thiery <heiko.thiery@...il.com>,
        Fabio Estevam <festevam@...il.com>
Subject: Re: [PATCH 6/6] arm64: dts: imx8mm-kontron: Add support for reading
 SD_VSEL signal

On 2/13/23 17:15, Marco Felsch wrote:

[...]

>> @@ -347,7 +347,7 @@ MX8MM_IOMUXC_SD2_DATA1_USDHC2_DATA1		0x1d6
>>   			MX8MM_IOMUXC_SD2_DATA2_USDHC2_DATA2		0x1d6
>>   			MX8MM_IOMUXC_SD2_DATA3_USDHC2_DATA3		0x1d6
>>   			MX8MM_IOMUXC_SD2_CD_B_GPIO2_IO12		0x019
>> -			MX8MM_IOMUXC_GPIO1_IO04_USDHC2_VSELECT		0x1d0
>> +			MX8MM_IOMUXC_GPIO1_IO04_USDHC2_VSELECT		0x400001d0
> 
> The VSELECT pin should be driven by the (u)sdhc core...
> 
>>   		>;
>>   	};
>>   };
>> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-osm-s.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-kontron-osm-s.dtsi
>> index 5172883717d1..90daaf54e704 100644
>> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-osm-s.dtsi
>> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-osm-s.dtsi
>> @@ -196,6 +196,7 @@ reg_nvcc_sd: LDO5 {
>>   				regulator-name = "NVCC_SD (LDO5)";
>>   				regulator-min-microvolt = <1800000>;
>>   				regulator-max-microvolt = <3300000>;
>> +				sd-vsel-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> 
> and by using the sd-vsel-gpios property the IOMUXC_GPIO1_IO04 have to be
> muxed as GPIO, which is not the case. So I think that u-boot have a bug
> within the (u)sdhc core.

The trick here is that the VSELECT is operated by the usdhc block as a 
function pin, but the PMIC driver can read the current state of the 
VSELECT pin by reading out the GPIO block SR register. Since the IOMUX 
SION bit is set on the VSELECT pin, the state of the pin is reflected in 
the GPIO block SR register even if the pin is muxed as function pin.