STM32MP157 ADC failing to probe during boot

[LinuxAddict]

Greeting.

I'm trying to get our ADC subsystem up and running and getting weird errors in dmesg during boot. I'm assuming I've done something wrong with devicetree but I can't seem to figure out a working combination from the docs.

Full part number of our MPU is STM32MP157CAC3.

During boot we get error -61 during the probe of the two converters as shown below

Thanks,

-LinuxAddict

$ dmesg | grep -E "adc|iio"
[ 2.510869] iio iio:device0: No channels configured
[ 2.514812] stm32-adc: probe of 48003000.adc:adc@0 failed with error -61
[ 2.522467] iio iio:device0: No channels configured
[ 2.526055] stm32-adc: probe of 48003000.adc:adc@100 failed with error -61

Here's our devicetree portions:

&pinctrl {
    adc1_pins: adc1-single-ended {
        analog-inputs1 {
            pinmux = <STM32_PINMUX('C', 0, ANALOG)>,
                     <STM32_PINMUX('A', 5, ANALOG)>;
            bias-disable;
        } ;
    } ;
};

&adc {
    pinctrl-names = "default";
    pinctrl-0 = <&adc1_pins>;
    status = "okay";
    vdda-supply = <&vdd>;
    vref-supply = <&v3v3>;

    /* ANALOG_IN1 = ADC2_INP0 (pin ANA0) */
    /* ANALOG_IN2 = ADC2_INP1 (pin ANA1) */
    /* ANALOG_IN3 = ADC1_INP10 (pin PC0) */
    /* ANALOG_IN4 = ADC1_INP19 (pin PA5) */

    adc1: adc@0 {
        status = "okay";
        channel@0 {
            reg = <0>;
            st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
            label = "ANALOG_IN_1";
        };
        channel@1 {
            reg = <1>;
            st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
            label = "ANALOG_IN_2";
        };
    };

    adc2: adc@100 {
        status = "okay";
        channel@10 {
            reg = <10>;
            st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
            label = "ANALOG_IN_3";
        };
        channel@19 {
            reg = <19>;
            st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
            label = "ANALOG_IN_4";
        };
    };
};

[Gregory PLANCHON]

Hi @LinuxAddict ,

Have you checked the various wiki pages to see if you've missed anything? 

https://wiki.st.com/stm32mpu/wiki/ADC_device_tree_configuration

https://wiki.st.com/stm32mpu/wiki/ADC_OpenSTLinux_drivers

Regards,

Grégory

[LinuxAddict]

Gregory,

Yes, thank you for the response.

I've consulted both of the wiki pages paying especially careful attention to the ADC device tree page to no avail.

Thanks,

-Adrian

[Gregory PLANCHON]

Hi @LinuxAddict ,

Could you check these different points, please:

• Are you sure about the pinctrl you indicated?
• Are you sure your power supply is correct and properly configured?
• Are you sure you're on the right channels? 

Regards,

Grégory

[LinuxAddict · Accepted solution]

In case anyone else runs into these issues, I didn't understand that functioning ADC/IIO driver is silent in the kernel logs. It was actually working the whole time.