topic i.MX35 Setting SD2 gpio to pull up in i.MX Processors

i.MX35 Setting SD2 gpio to pull up

frk — Tue, 01 Sep 2020 08:54:34 GMT

Hi all,

I'm trying to activate a new input on my i.MX35 device MX35_PAD_SD2_DATA3__GPIO2_4 and activating the pull up mode to this input.

But I'm a bit confused with the device tree configuration :

gpio_exporter: gpio-exporter {
compatible = "linux,gpio-exporter";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpio_exporter>;

GPIO_IN {
gpios = <&gpio3 13 GPIO_ACTIVE_HIGH>;
};

GPIO_OUT {
gpios = <&gpio3 12 GPIO_ACTIVE_HIGH>;
output;
initial-state = <0>;
};

...

GPIO_NEWINPUT {
gpios = <&gpio2 4 GPIO_ACTIVE_HIGH>;
};
};

pinctrl_gpio_exporter: gpioexportergrp {
fsl,pins = <

MX35_PAD_RTS2__GPIO3_12 0x80000000
MX35_PAD_CTS2__GPIO3_13 0x80000000
...
MX35_PAD_SD2_DATA2__GPIO2_4 0x80000000
>;
};

Others GPIOs use the 0x80000000 value but what is it's meaning?

I have take a look to Table 301: Register: IOMUXC_SW_MUX_CTL_PAD_SD2_DATA2 but this subject is not clear enough for me.

I also have check in my include/dt-bindings/gpio/gpio.h file and no reference to pull up configuration.

igorpadykov — Tue, 01 Sep 2020 11:00:06 GMT

Hi frk

0x80000000 means that settings are inherited from uboot ( pin does not need config.)

More details can be found in AN5078

Field "PULL_KEEP_CTL" Register: IOMUXC_SW_PAD_CTL_PAD_SD2_DATA3 configures

Best regards
igor

frk — Tue, 01 Sep 2020 11:11:57 GMT

So if 0x80000000 is used and nothing come from the bootloader, state can be considered as unknown/invalid?

I'll check the documentation, AN5078 seems pretty usefull.

igorpadykov — Tue, 01 Sep 2020 12:45:46 GMT

>So if 0x80000000 is used and nothing come from the bootloader, state can be considered as unknown/invalid?

it is set as default state (after reset)

~igor

frk — Tue, 01 Sep 2020 14:12:30 GMT

Thanks for your support.

Things are clearer now.