Thanks to Stephen’s advise , I’ve managed to get access to U-Boot command line.
I have enabled the gpio command (CONFIG_CMD_GPIO=y) in the U-Boot configuration.
I have enabled the used gpios in the /arch/arm/dts/rk3399pro-rockpi-n10-linux.dts
&gpio0 {
status = "okay";
};
&gpio1 {
status = "okay";
};
&gpio2 {
status = "okay";
};
However, I still can’t access GPIOs from U-Boot. gpio status -a returns empty line.
I had to add in the arch/arm/dts/rk3399-u-boot.dtsi the following definitions:
&pinctrl {
status = "okay";
u-boot,dm-pre-reloc;
};
&gpio0 {
status = "okay";
u-boot,dm-pre-reloc;
};
&gpio1 {
status = "okay";
u-boot,dm-pre-reloc;
};
&gpio2 {
status = "okay";
u-boot,dm-pre-reloc;
};
After the above, the gpio status -a started to report the GPIOs.
Looking for the right solution I have also set CONFIG_SPL_GPIO_SUPPORT=y in the U-Boot configuration. I have not verified yet if that is really needed.