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4.0.2 Tick timing incorrect after swapping clock configuration

Question asked by FRED WEDEMEIER on Jan 26, 2017
Latest reply on Feb 4, 2017 by FRED WEDEMEIER

Very long story made short, it appears that tick timing get bollixed after changing clock configurations.

Demo this by:

  printf( "pre: %d\n", _time_get_hwticks_per_tick() );

_bsp_set_clock_configuration( <config other than startup> );

  printf( "post: %d\n", _time_get_hwticks_per_tick() );


pre and post values the same... If core clock changes, _hwticks_per_tick should change.

Result of not changing is that time becomes non-monotonic.


If this a bug and not something messed up in my BSP, the bug is in _bsp_set_clock_configuration()

- It calls CPU_SetClockConfiguration()

- then calls hwtimer_set_freq() to update the timer modulo, but does not update kernel_data->HW_TICKS_PER_TICK

- exits.

- any following tick-related call uses the bogus kernel_data->HW_TICKS_PER_TICK


In my BSP, I fixed the problem by calling _time_set_hwticks_per_tick() after the call to hwtimer_set_freq()


NXP: Bug in MQX or something mucked up in my BSP as it was built?


Also, in the process of chasing this down I came across _time_set_resolution() which states:

     kernel_data->HW_TICKS_PER_TICK = resolution * 1000;

... which is not correct.