[PATCH 8/8] arm64: dts: rockchip: Enable SD-card interface on Radxa E20C

[Jonas Karlman]

Hi,

On 2025-03-01 11:48, Yao Zi wrote:
> SD-card is available on Radxa E20C board.
> 
> Signed-off-by: Yao Zi <ziyao at disroot.org>
> ---
>  arch/arm64/boot/dts/rockchip/rk3528-radxa-e20c.dts | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3528-radxa-e20c.dts b/arch/arm64/boot/dts/rockchip/rk3528-radxa-e20c.dts
> index d2cdb63d4a9d..473065aa4228 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3528-radxa-e20c.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3528-radxa-e20c.dts
> @@ -12,6 +12,10 @@ / {
>  	model = "Radxa E20C";
>  	compatible = "radxa,e20c", "rockchip,rk3528";
>  
> +	aliases {
> +		mmc0 = &sdmmc;

Suggest using mmc1 for sd-card because the e20c typically have onboard
emmc, compared to removable sd-card.

> +	};
> +
>  	chosen {
>  		stdout-path = "serial0:1500000n8";
>  	};
> @@ -20,3 +24,13 @@ chosen {
>  &uart0 {
>  	status = "okay";
>  };
> +
> +&sdmmc {
> +	bus-width = <4>;
> +	cap-mmc-highspeed;
> +	cap-sd-highspeed;
> +	disable-wp;
> +	rockchip,default-sample-phase = <90>;
> +	sd-uhs-sdr104;

Are you sure uhs-sdr104 works as is should? Vendor kernel use a
different "v2" tuning and this is also missing the vccio_sd vqmmc-supply
to switch between 3v3 and 1v8.

You could add following regulator for sdmmc:

	vccio_sd: regulator-vccio-sd {
		compatible = "regulator-gpio";
		gpios = <&gpio4 RK_PB6 GPIO_ACTIVE_HIGH>;
		pinctrl-names = "default";
		pinctrl-0 = <&sdmmc_vol_ctrl_h>;
		regulator-name = "vccio_sd";
		regulator-min-microvolt = <1800000>;
		regulator-max-microvolt = <3300000>;
		states = <1800000 0x0>, <3300000 0x1>;
	};

and following pinctrl:

	sdmmc {
		sdmmc_vol_ctrl_h: sdmmc-vol-ctrl-h {
			rockchip,pins = <4 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>;
		};
	};

add then the power supplies to the sdmmc node:

	vmmc-supply = <&vcc_3v3>;
	vqmmc-supply = <&vccio_sd>;

That matches the schematics for e20c, and works when testing non-uhs modes.

Regards,
Jonas

> +	status = "okay";
> +};