Using DEVICE_LPTICKER on STM32L486

[TacoGrandeTX]

Description

@jeromecoutant Could we please get some clarification on the removal of LPTICKER for some STM32L4 targets in c31a7c2 ?

Are there precautions that can be taken to still make use of DEVICE_LPTICKER?

We have a customer interested in using MBED_TICKLESS with DEVICE_LPTICKER on a Advantech WISE-1570 (STM32L486-based) and they are experiencing a hang when normal sleep is entered with ThisThread::sleep_for() for 8 seconds or more.

This is only observed on Mbed OS v5.10.x. It's okay on Mbed OS v5.9 with Thread::wait().

Issue request type

[X] Question
[ ] Enhancement
[ ] Bug

[jeromecoutant]

Hi

LPTICKER has not been removed... Feature has just been moved from target definition to family definition.

For MTB_ADV_WISE_1570,
you should remove "device_has_remove": ["LPTICKER"],

I can advice to check NUCLEO_L486RG configuration and add:
"lpticker_lptim": {
"help": "This target supports LPTIM. Set value 1 to use LPTIM for LPTICKER, or 0 to use RTC wakeup timer",
"value": 1
}

[TacoGrandeTX]

@jeromecoutant Thank you for that... I was concerned that it was not a valid run-time option. As mentioned our customer is seeing hangs on the MTB_ADV_WISE_1570 with MBED_TICKLESS and LPTICKER defined on OS v5.10. It runs fine if MBED_TICKLESS is removed or if run on v5.9.x. Locally this doesn't fail on a Nucleo-L476, but we don't have access to a L486-based target.

Do you have thoughts on why the attached program is hanging?

Could there be a regression on these recent PRs ?
#7524
#8427

reproducer.zip

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-211

[TacoGrandeTX]

@jeromecoutant Additional testing has shown that increasing LPTICKER_DELAY_TICKS to 4 prevents the hang.

[jeromecoutant]

Thx @TacoGrandeTX for this report

Maybe I should set this 4 tick value for all targets.
Will start tests in TICKLESS

@c1728p9 @LMESTM

[jeromecoutant]

New LPTICKER_DELAY_TICKS value is part of #9134

[screamerbg]

@TacoGrandeTX Does this answer your question? Mbed OS 5.11.1 contains patch to address this.

[TacoGrandeTX]

@screamerbg Yes - will close. Thanks for the followup.