AM623: How to set up the software when using μSD

Hello,

Please refer to the following DTS node used for voltage switch to support UHS speed modes:

https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/arch/arm/dts/k3-am625-sk.dts?h=09.02.00.010&id=83660642085462346fbeb410f83bc99448ec7042#n147

❯ grep -A13 "vdd_sd_dv:" -- ./arch/arm/dts/k3-am625-sk.dts
        vdd_sd_dv: regulator-4 {
                /* Output of TLV71033 */
                compatible = "regulator-gpio";
                regulator-name = "tlv71033";
                pinctrl-names = "default";
                pinctrl-0 = <&vdd_sd_dv_pins_default>;
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <3300000>;
                regulator-boot-on;
                vin-supply = <&vcc_5v0>;
                gpios = <&main_gpio0 31 GPIO_ACTIVE_HIGH>;
                states = <1800000 0x0>,
                         <3300000 0x1>;
        };

Regards,

Prashant

Hi Prashant   

Thank you for the answer.

 I understand how to configure VSEL_SD.

gpios = <&main_gpio0 31 GPIO_ACTIVE_HIGH>;  ←　GPIO to reset the VSEL_SD terminal of the PMIC 

But, When SD card back to 3.3V mode after it was changed to operate in 1.8V mode,  Where should I set the ”en” signal GPIO to reset the power supply of the μSD?

>[FAQ] AM625: SD card (MMC1) VDD power supply

> Having the reset capability is very important for UHS-I SD Cards because this is the only way to force the SD Card back to 3.3V mode after it was changed >to operate in 1.8V mode.

Regards 

Shungo

Hi team

I would like to ask an additional question.

1.Like the reference board, the regulator is TPS2918DBVR and Vin is 3.3V, but what part of this program should I modify?

2.Is it correct to understand that once the transmission speed is decided, it is automatically controlled via GPIO?

Hello,

SHUNGO MIYATA said:

Like the reference board, the regulator is TPS2918DBVR and Vin is 3.3V, but what part of this program should I modify?

Please refer to the `vmmc-supply` and `vqmmc-supply` properties of the SD card node (sdhci1) for the SD card and the I/O supply voltage respectively.

You would need to modify the assigned notes to these properties according to your schematics.

For TI SK-AM62B EVM, the SD card and I/O supply is controlled through the IO Expander & GPIO respectively as shown:

SHUNGO MIYATA said:

Is it correct to understand that once the transmission speed is decided, it is automatically controlled via GPIO?

The initialization sequence is part of the driver. You would need to only modify the DTS to define the way to control the SD card and I/O supply.

Regards,

Prashant

Hi Prashant

Thank you for your answer.

VSEL_SD is connected to PMIC TPS6521902, not TLV71033. In that case, do I need to modify the following part?

The μSD circuit part is almost the same as the SK-AM62-LP circuit diagram.

vdd_sd_dv: regulator-4 {
/* Output of TLV71033 */
compatible = "regulator-gpio";                             
regulator-name = "tlv71033";       　　　　　　　←not need modify?（not use other program?)
pinctrl-names = "default";
pinctrl-0 = <&vdd_sd_dv_pins_default>;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <3300000>;
regulator-boot-on;
vin-supply = <&vcc_5v0>;                                    ←not need modify?（not use other program?)
gpios = <&main_gpio0 31 GPIO_ACTIVE_HIGH>;  ←only change  gpio0_91(In my circuit use this port)
states = <1800000 0x0>,
<3300000 0x1>;
};

regrads 

shungo

Hello,

Before going further with integrating the VSEL_SD control in the DTS, do you have the working boot setup with SD card in HS mode, which doesn't require 1.8V support, only?

If yes, could you please share the successful boot logs?

If not, could you first try the SD card in HS mode as described here:

https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/09_02_01_09/exports/docs/linux/Foundational_Components/U-Boot/UG-Memory.html#booting-tiboot3-bin-tispl-bin-and-u-boot-img-from-emmc-boot-partition-for-k3-class-of-socs:~:text=Restricting%20to%20a%20given%20speed%20mode

Regards,

Prashant

Hi Prashant 

Right now, we are writing the specifications to make the circuit work, so we are currently in the process of checking what needs to be corrected first.

regards

shungo.