Colibri iMX6ULL: Using other SD card modes

Hi team,

A customer is trying out some faster modes in Colibri iMX6ULL and have some questions.

  1. The customer would like to specify the mode (DDR50, SDR104, etc.). So far, they’ve succesfully changed the device tree to get up to the SDR104.

dmesg | grep mmc
mmc0: new ultra high speed SDR104 SDIO card at address 0001

However, they would like to know if it is possible to use other modes. They’ve tried ie. setting the clock at 50MHz (DDR50), but they get the same “SDR104” initialization message. Any idea?

&usdhc1 {
max-frequency = <50000000>; //50MHz
  1. It seems that when initializating the SDIO, there is a brief time where the interface starts at 3.3V, then a command through CMD11 is sent and the switch is made. Is it possible to make a change so that the interface is directly initialized at 1.8V? They tried the following change in imx6ull-colibri.dtsi:
&usdhc1 {
vqmmc-supply = <&reg_sd1_vqmmc>;

reg_sd1_vqmmc: regulator-sd1-vqmmc {

compatible = “regulator-gpio”;
gpios = <&gpio5 9 GPIO_ACTIVE_HIGH>;
pinctrl-names = “default”;
pinctrl-0 = <&pinctrl_snvs_reg_sd>;
regulator-name = “+V3.3_1.8_SD”;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <3300000>;
states = <1800000 0x1 1800000 0x0>;
vin-supply = <&reg_module_3v3>;


The above seems to be working fine to force 1.8V at all time.