SOFT 298: delay_us implemented without soft timer

[selinahsu]

No description provided.

[ShiCheng-Lu]

I could change x86 implementation to be more similar to STM32, if that is desired?

[ShiCheng-Lu]

Now, do I know why test_bts7040_enable_fails_during_fault failed? Absolutely not...
seems like the callback isn't being called when a fault is set

  // Make sure fault clears after time elapsed and values return to normal
  delay_ms(40);
  TEST_ASSERT_TRUE(bts7040_get_output_enabled(&s_storage));

delay is preventing fault from being cleared?
maybe it's because the old delay uses wait() so the processor can process the fault clearing,
while the new delay without soft_timer needs to be a busy loop?

[ryandancy]

No full review yet (I was trying to get it to work on the hardware I have and it's decided not to work) but one question: is there a reason we still need the soft timer solution when not in an interrupt if your other solution works?

[ryandancy]

Also I'm pretty sure that time.h etc should work on stm32 (unless you got a compile error in which case never mind) - the stm32 standard library we use is called newlib (source downloadable/searchable at that link) and I think all the libraries are implemented. @ShiCheng-Lu

[ShiCheng-Lu]

What on earth? :< We've got quite a few problems here.
time.h with newlib doesn't have the functions to get micro-second precision. (only seconds)

at least on x86, the time with clock_gettime() is ever so slightly faster than times in soft_timer which uses timers that rely in interrupt. so a lot of delays become just short enough to break most tests that use soft_timer to do some action.

although it might be accurate on stm32 as rightnow it is using the same time TIM2 that soft_timer uses. But that build did fail with bts7040 test in ms-drivers. Do not know why.

I would probably suggest leaving delay_us implemented with soft timers, and forbid the use of delay_us() in callbacks. Implement another delay function with system clock that is slightly less accurate to the rest of the program if delay is ever needed in a callback.
Other option is the way I have it now, where it checks if interrupts are enabled, and uses soft_timer or sys time accordingly.