NRF52_DK sleep/deep sleep profiling does not work

[JuricaResetar]

Description

Hi =)

[X ] Bug
I'm trying to implement sleep/deep sleep profiling into my project on Nordic's NRF52_DK but with no success. I'm using official mbed-os version mbed-os-5.9.6 and mbed CLI with GCC_ARM compiler.
I've followed instructions from mbed web and added MBED_SLEEP_TRACING_ENABLED macro into my mbed_app.json file but with no success.
I'm quite sure my printf and mbed_app.json part work because this example for mbed statistics works great and the principle is the same (one macro and print on standard IO).

I have found the same problem description on mbed forum here.

I wunder if there's some kind of fix for that or should I have for new version of mbed-os?

Here's the main file (the one from official example on mbed-os):

#include "mbed.h"

int main()
{
	while(1)
	{
		// Deep sleep for 1 second
		printf("Deep sleep allowed: %i\r\n", sleep_manager_can_deep_sleep());
		wait(1.0);

		// Lock deep sleep
		printf("Locking deep sleep\r\n");
		sleep_manager_lock_deep_sleep();

		// Sleep for 1 second
		printf("Deep sleep allowed: %i\r\n", sleep_manager_can_deep_sleep());
		wait(1.0);
	}
}

[TacoGrandeTX]

This is not working for two reasons:

1. As mentioned in the forum post you will need to have DEVICE_STDIO_MESSAGES defined as this enables the print messages that the tracer produces.
2. Even with DEVICE_STDIO_MESSAGES we noticed that the trace messages were stalled waiting on a mutex. This is fixed by this PR which was just reviewed: NRF52: serial_api: Use polling for putc #8048

Please bring in the above and try it again.

We'll update the Forum post for those that aren't tracking GitHub.

[Mirrored to Jira]

[adbridge]

Internal Jira reference: https://jira.arm.com/browse/IOTDEV-1634