How do I set clock-rates of usdhc2 in imx8mm?

[takeshi100]

Hi.

I have question about usdhc2 in imx8mm.

■ Question

1. Why are there pinctl-0, 1, 2? not only one?
2. How clock rate is minimum(or range) of usdhc2?

3. if I want to change clock rate, Should I set to assigned-clock-rate?

■supplement(imx8mm-evk.dtsi)
&usdhc2 {
assigned-clocks = <&clk IMX8MM_CLK_USDHC2>;
assigned-clock-rates = <200000000>;
pinctrl-names = "default", "state_100mhz", "state_200mhz";
pinctrl-0 = <&pinctrl_usdhc2>, <&pinctrl_usdhc2_gpio>;
pinctrl-1 = <&pinctrl_usdhc2_100mhz>, <&pinctrl_usdhc2_gpio>;
pinctrl-2 = <&pinctrl_usdhc2_200mhz>, <&pinctrl_usdhc2_gpio>;
cd-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;
bus-width = <4>;
vmmc-supply = <&reg_usdhc2_vmmc>;
status = "okay";
};

[joanxie · Accepted solution]

1) you can refer to the document, pinctrl-0 is required, pinctrl-1 and pinctrl-2 are optional , but for usdhc, the minimum is 3 or 1

https://github.com/nxp-imx/linux-imx/blob/lf-6.6.y/Documentation/devicetree/bindings/pinctrl/pinctrl...

2) pls refer to the chapter 3.9.2 Ultra-high-speed SD/SDIO/MMC host interface (uSDHC) AC
timing of i.mx8mm data sheet

3) yes