stm32mp157-dk2 How to enable vdda and vref regulators

[Alex Mach]

Hello,

My app running on M4 uses adc. It starting at kernel boot process using systemd. After some time kernel poweroff vdda and vref while my app is running

[  14.173564] remoteproc remoteproc0: powering up m4

[  14.308543] remoteproc remoteproc0: Booting fw image OpenAMP_TTY_echo_CM4.elf, size 2541404

[  14.361095] virtio_rpmsg_bus virtio0: rpmsg host is online

[  14.370223] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-channel addr 0x0

[  14.389900] mlahb:m4@10000000#vdev0buffer: registered virtio0 (type 7)

[  14.399505] rpmsg_tty virtio0.rpmsg-tty-channel.-1.0: new channel: 0x400 -> 0x0 : ttyRPMSG0

[  14.408052] remoteproc remoteproc0: remote processor m4 is now up

[  14.422284] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-channel addr 0x1

[  14.455735] rpmsg_tty virtio0.rpmsg-tty-channel.-1.1: new channel: 0x401 -> 0x1 : ttyRPMSG1

[  34.411305] vref: disabling

[  34.413987] vdda: disabling

and my app can't process adc.

So how to prevent disabling vref and vdda?

Thanks,

Alex.

[PatrickF]

Hello,

https://wiki.st.com/stm32mpu/wiki/How_to_configure_system_resources#ADC_example will probably help you.

Regards.

[Alex Mach · Accepted solution]

Hello Patrick,

My dts files include all defines described your link but vref & vdda disabling by kernel. If I run m4 app after this disabling adc works fine (so app enabled vref and vdda).

PS: I've changed regulator-boot-on to regulator-always-on in dts file. It works.

Thanks,

Alex.

[PatrickF]

Hello,

Sorry for late answer.

Seems regulator-always-on is not needed if you enable the resource manager in the DT as stated in the wiki.

As I understand, this will tell Linux to bind M4 resources to remoteproc status to avoid shutting down VDDA if Cortex-M4 is running.

&m4_rproc {
	m4_system_resources {
		status = "okay";
	};
};

Regards,

Patrick