With Zephyr 3.6.0 control is not coming out from STOP3 mode

[ritumohan]

I am working with STM32 U575/U5A5 series of STM controller in low power modes. I have programmed the controller to enter into STOP3 mode using HAL driver, not using zephyr provided API's and wake up from STOP3 mode based on Wakeup pin(High on PF2).

Code is working fine with Zephyr 3.2.0, but with zephyr 3.6.0, control is not coming out from STOP3 mode even after wakeup pin is made high.

Below config's are disabled since HAL drivers is used to enter into STOP3 mode
CONFIG_PM=n
CONFIG_PM_DEVICE=n
CONFIG_PM_DEVICE_RUNTIME=n
CONFIG_PM_POLICY_DEFAULT=n

can anyone help me to figure out the issue.

@erwango @FRASTM

Thanks,
Mohan

[ritumohan]

I'm able to reproduce this issue with blinky example aswell. Enabled RTC and RTC wakeup timer on top of blinky example and tested the changes in both zephyr 3.2.0 and zephyr 3.6.0.
With zephyr 3.2.0 it is working as expected, but with zephyr 3.6.0 it is not coming out from STOP 3 mode, but if we do power cycle the control after flash, it is working as expected. Not sure why with zephyr 3.6.0 power cycle is required.

Attaching the patch for your reference, you can apply the patch on top of the blinky sample to understand the issue. You can monitor LED or serial console to know whether control is out from STOP mode or not.

Example path: zephyr\samples\basic\blinky
LowPower_3_6_0.patch
LowPower_3_2_0.patch

@erwango @FRASTM

[JarmouniA]

@ritumohan v3.6.0 is no longer supported, can you retest with v3.7.0?

[ritumohan]

@JarmouniA I tried with zephyr 3.7.0 as well getting same issue. Attaching the patch file for your reference, you can use the patch file to recreate the issue at your end.
LowPower_3_7_0.patch

[JarmouniA]

@ritumohan Also, Stop3 mode support was added in v3.7.0 for STM32U5, see https://github.com/zephyrproject-rtos/zephyr/tree/v3.7-branch/samples/boards/stm32/power_mgmt/stop3