Question
STM32 ADC UBoot Driver failing when trying to enable ADC voltage regulator (ADVREGEN)
I'm trying to perform ADC using PA3 (adc1_in15) and PF11(adc1_in2) pins of stm32mp157c-ev1 board but I keep getting "stm32-adc adc@0: Failed to enable vreg: -110"
In arch/arm/dts/stm32mp157c-ev1-u-boot.dtsi I added the following:
&adc {
/* ANA0, ANA1 are dedicated pins and don't need pinctrl: only in6. */
pinctrl-0 = <&adc1_ain_pins_a>;
pinctrl-names = "default";
vdd-supply = <&vdd>;
vdda-supply = <&vdda>;
vref-supply = <&vdda>;
status = "okay";
adc1: adc@0 {
status = "okay";
/delete-node/ channel@0;
/delete-node/ channel@1;
/delete-node/ channel@6;
channel@2 {
reg = <2>;
/* 16.5 ck_cycles sampling time */
st,min-sample-time-ns = <400>;
};
channel@15 {
reg = <15>;
st,min-sample-time-ns = <400>;
};
};
};
After comparing the drivers between the kernel and uboot, I found out that the UBoot's stm32-adc-core driver does not enable the VDDA/VDD and VREF regulators. Thus, I tried to patch
stm32_adc_core_probe so VDDA/VDD and VREF regulators will get enabled (I used). After patching it, I verified that the issue got fixed and was able to perform ADC.
regulator_set_enable_if_allowed API from regulator.h to enable them)
I would like to understand whether this is a driver issue or DTS issue? If it is a driver problem, please patch it as I'm not an familiar with contributing to the community and got no idea about the SOP for patching a driver. Thanks!