ADC and DAC not working

[Julius Salamon]

Hello,

I made a custom image for the brk board like described in the CubeMX tutorial.
The image is running normaly on the brk board and i can also launch M4 programs.
The problem is that the ADC and DAC are not working even though I enabled them in cube MX.
When the boot process is finished linux prints: vdda: disabling. I think thats the reason for the problem.
I try to fix this by setting ldo5 to regulator-always-on manualy in the device tree. But it ignores that.

I also tried the following device tree https://github.com/octavosystems/OSD32MP1-BRK-device-tree/tree/master/linux-v5.10-r0.
Here the regulator-always-on works and also the adc is running as expected. But the DAC is not working, probally because it is not enabled in the devicetree. I dont want to learn how to define the peripherals by hand in the devicetree so I did not test if the DAC would work in this case.

Is there a solution for this problem?
How can I prevent vdda from disabling or how can I reanable it?

I also attached my devicetree file.
I would be very gratefull for any help.

Best Regards
Julius Salamon

[Neeraj Dantu]

Hey Julius,

Using the device tree is the recommended way to control power rails of the PMIC. See example here for EV1 board: https://github.com/STMicroelectronics/linux/blob/v5.15-stm32mp/arch/arm/boot/dts/stm32mp15xx-edx.dtsi#L175.

Please also take a look at the EV1 implementation of ADC and DAC here: https://github.com/STMicroelectronics/linux/blob/v5.15-stm32mp/arch/arm/boot/dts/stm32mp15xx-edx.dtsi#L108 and https://github.com/STMicroelectronics/linux/blob/v5.15-stm32mp/arch/arm/boot/dts/stm32mp15xx-edx.dtsi#L146

Best,

Neeraj

[coloradocarlos]

(I tried to post this response last week, but it didn’t seem to go through.)

By default, regulators are disabled if there are no consumers. The idea is if a regulator is not supplying power to anything (consumers), it can be safely turned off.  This is what you are seeing in dmesg. Once a consumer is enabled, the regulator is also re-enabled.

If you have debugfs enabled, then you may be able to see where vdda is being used in the regulator tree:

# less /sys/kernel/debug/regulator/regulator_summary

I suspect that vdda is not configured as a supply or the device tree node is not status=okay. Can you post your adc and dac nodes in your device tree?

Carlos

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