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ARM-software / CMSIS-FreeRTOS

FreeRTOS adaptation for CMSIS-RTOS Version 2
https://arm-software.github.io/CMSIS-FreeRTOS/
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Auto clear overflow flag in SysTick_Handler(cmsis_os2) will break `configUSE_TICKLESS_IDLE 1` in freeRTOS #60

Closed yyjdelete closed 1 year ago

yyjdelete commented 1 year ago

Seems SysTick_Handler in cmsis_os2 will auto clear overflow flag for SysTick_Handler https://github.com/ARM-software/CMSIS-FreeRTOS/blob/9cf2e4b4f621abfed0ee2de421d31988f8b1b0f6/CMSIS/RTOS2/FreeRTOS/Source/cmsis_os2.c#L152-L158

But it will also break the default implementation of vPortSuppressTicksAndSleep (#define configUSE_TICKLESS_IDLE 1), which required to check the same flag, and it make the wakeup timer almost frozen. https://github.com/ARM-software/CMSIS-FreeRTOS/blob/3da36094e21d6fed61719ecf9bb3530a11fd2bb0/Source/portable/GCC/ARM_CM3/port.c#L552-L566

Is there any way to fix the conflict?

VladimirUmek commented 1 year ago

Hi, thanks for bringing that up! SysTick_Handler in cmsis_os2 clears overflow flag to enable correct functionality of osKernelGetSysTimerCount. It does not seem like there will be an easy workaround. We need to investigate this issue and see what can be done.

VladimirUmek commented 1 year ago

Hi, please see the referenced commit: SysTick_Handler was updated: https://github.com/ARM-software/CMSIS-FreeRTOS/blob/13acfbef7be85119fc6bc56832c455d4547d92c7/CMSIS/RTOS2/FreeRTOS/Source/cmsis_os2.c#L156-L161

and as a consequence also osKernelGetSysTimerCount had to be updated:

https://github.com/ARM-software/CMSIS-FreeRTOS/blob/13acfbef7be85119fc6bc56832c455d4547d92c7/CMSIS/RTOS2/FreeRTOS/Source/cmsis_os2.c#L475-L516

Do you have any concerns related to the implemented workaround?