Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

Susheel Nuguru — Mon, 31 Aug 2020 11:52:48 GMT

I took a look at it and replied. Please use that thread to respond and not here.

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

dfer — Mon, 31 Aug 2020 11:06:59 GMT

Hi Susheel I've posted this topic:

devzone.nordicsemi.com/.../interrupts-not-waking-freertos-up-in-tickless-mode

if you could help it would be very appreciated.

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

Susheel Nuguru — Wed, 26 Aug 2020 13:04:12 GMT

[quote user="dfer"]Are you going to integrate this in the SDK? [/quote]

Yes Davide,

This fix will go into the SDK after some testing.

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

dfer — Wed, 26 Aug 2020 12:56:22 GMT

Thank you Susheel

Yes so actually you emulate in vPortSuppressTicksAndSleep what the interrupt already does.

So our solutions are similar. I'll consider to move to your solution. Are you going to integrate this in the SDK?

Regards.

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

Susheel Nuguru — Wed, 26 Aug 2020 12:23:42 GMT

Hi Davide,

You have done a nice investigation. This is actually a bug in the tick handling and I have recently come to have known of it from this thread.

The issue in both of the threads is identified correctly. xTaskIncrementTick has a special meaning for FreeRTOS as it also hints the scheduling changes. But for the diff more than 1 this was not handled correctly.

In my last reply in the given thread, I have proposed a similar but smaller workaround that seems to work as intended.

The change is to call xTaskIncrementTick irrespective of the tick is greater or equal to one.

RE: Tickless implementation using RTC causes FreeRTOS idle to loop for one tick

dfer — Tue, 25 Aug 2020 12:00:28 GMT

As info, the actual delayed Task is activated in xTaskResumeAll, because the uxPendedCounts variable is found set.

This variable is incremented in the tick Interrupt when the function xTaskIncrementTick isc called (after the __WFE, in my solution). The Scheduler is locked at this time, so that the only thing done is incrementing this variable.

But of Course, if the function xTaskIncrementTick is not called, the variable is not incremented and the mentioned Problem happens.