When both tickless and LPTICKER_DELAY_TICKS are enabled some ST
devices randomly get stuck sleeping forever. This is because the
wake up time passed to the rtc is ignored if the previous match is
about to occur. This causes the device to get stuck in sleep.
This patch prevents matches from getting dropped by the rtc by
deactivating the rtc wake up timer before setting a new value.
Events leading up to this failure for the RTC:
-1st call to lp_ticker_set_interrupt
-delay until ticker interrupt is about to fire
-2nd call to lp_ticker_set_interrupt
-interrupt for 1st call fires and match time for 2nd call is dropped
-LowPowerTickerWrapper gets ticker interrupt but treats it as a
spurious interrupt and drops it since it comes in too early
-device enters sleep without a wakeup source and locks up
This PR provides implementation of ticker_free() function for the following boards:
ARCH_PRO
EV_COG_AD3029LZ
EV_COG_AD4050LZ
K22F
K64F
K82F
KW24D
KW41Z
LPC546XX
NRF51_DK
NRF52_DK
NUCLEO_F207ZG
NUCLEO_F401RE
NUCLEO_F429ZI
NUCLEO_F746ZG
REALTEK_RTL8195AM
STM32L0, L4, F7 and few F4 chip are supporting LPTIM feature.
We propose to allow user to use LPTIM for MBED LowPowerTimer API instead of using RTC wakeup timers.
By default, all targets that are supporting this feature have been configured.
fire_interrupt function should be used for events in the past. As we have now
64bit timestamp, we can figure out what is in the past, and ask a target to invoke
an interrupt immediately. The previous attemps in the target HAL tickers were not ideal, as it can wrap around easily (16 or 32 bit counters). This new
functionality should solve this problem.
set_interrupt for tickers in HAL code should not handle anything but the next match interrupt. If it was in the past is handled by the upper layer.
It is possible that we are setting next event to the close future, so once it is set it is already in the past. Therefore we add a check after set interrupt to verify it is in future.
If it is not, we fire interrupt immediately. This results in
two events - first one immediate, correct one. The second one might be scheduled in far future (almost entire ticker range),
that should be discarded.
The specification for the fire_interrupts are:
- should set pending bit for the ticker interrupt (as soon as possible),
the event we are scheduling is already in the past, and we do not want to skip
any events
- no arguments are provided, neither return value, not needed
- ticker should be initialized prior calling this function (no need to check if it is already initialized)
All our targets provide this new functionality, removing old misleading if (timestamp is in the past) checks.
jeromecoutant
Martin Kojtal
Przemyslaw Stekiel
Bartek Szatkowski
Martin Kojtal