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Fix LowPowerTickerWrapper operation when suspended #8279

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Oct 26, 2018
Merged

Fix LowPowerTickerWrapper operation when suspended #8279

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023603f
Fix LowPowerTickerWrapper operation when suspended
fkjagodzinski Sep 27, 2018
effabc5
lp ticker wrapper: Add undefined behavior warning
fkjagodzinski Oct 19, 2018
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30 changes: 18 additions & 12 deletions hal/LowPowerTickerWrapper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,15 +32,7 @@ void LowPowerTickerWrapper::irq_handler(ticker_irq_handler_type handler)
{
core_util_critical_section_enter();

if (_suspended) {
if (handler) {
handler(&data);
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Even when suspended interrupts need to be passed through so higher layers can run tests.

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Please note the interrupts are passed as before. I moved _suspended to the next if statement to have the flags cleared (i.e. _pending_match).

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My bad, I didn't realize the interrupt was still getting through.

}
core_util_critical_section_exit();
return;
}

if (_pending_fire_now || _match_check(_intf->read())) {
if (_pending_fire_now || _match_check(_intf->read()) || _suspended) {
_timeout.detach();
_pending_timeout = false;
_pending_match = false;
Expand Down Expand Up @@ -78,6 +70,14 @@ void LowPowerTickerWrapper::resume()
{
core_util_critical_section_enter();

// Wait until rescheduling is allowed
while (!_set_interrupt_allowed) {
timestamp_t current = _intf->read();
if (((current - _last_actual_set_interrupt) & _mask) >= _min_count_between_writes) {
_set_interrupt_allowed = true;
}
}

_suspended = false;

core_util_critical_section_exit();
Expand Down Expand Up @@ -118,7 +118,7 @@ uint32_t LowPowerTickerWrapper::read()
core_util_critical_section_enter();

timestamp_t current = _intf->read();
if (_match_check(current)) {
if (!_suspended && _match_check(current)) {
_intf->fire_interrupt();
}

Expand All @@ -133,7 +133,13 @@ void LowPowerTickerWrapper::set_interrupt(timestamp_t timestamp)
_last_set_interrupt = _intf->read();
_cur_match_time = timestamp;
_pending_match = true;
_schedule_match(_last_set_interrupt);
if (!_suspended) {
_schedule_match(_last_set_interrupt);
} else {
_intf->set_interrupt(timestamp);
_last_actual_set_interrupt = _last_set_interrupt;
_set_interrupt_allowed = false;
}

core_util_critical_section_exit();
}
Expand Down Expand Up @@ -277,7 +283,7 @@ void LowPowerTickerWrapper::_schedule_match(timestamp_t current)
_intf->set_interrupt(_cur_match_time);
current = _intf->read();
_last_actual_set_interrupt = current;
_set_interrupt_allowed = false;
_set_interrupt_allowed = false;

// Check for overflow
uint32_t new_cycles_until_match = (_cur_match_time - current) & _mask;
Expand Down
3 changes: 3 additions & 0 deletions hal/LowPowerTickerWrapper.h
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Expand Up @@ -74,6 +74,9 @@ class LowPowerTickerWrapper {
*
* This stops to wrapper layer from using the microsecond ticker.
* This should be called before using the low power ticker APIs directly.
*
* @warning: Make sure to suspend the LP ticker first (call ticker_suspend()),
* otherwise the behavior is undefined.
*/
void suspend();

Expand Down
3 changes: 3 additions & 0 deletions hal/mbed_lp_ticker_wrapper.h
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Expand Up @@ -53,6 +53,9 @@ const ticker_data_t *get_lp_ticker_wrapper_data(const ticker_data_t *data);
*
* Pass through all interrupts to the low power ticker and stop using
* the microsecond ticker.
*
* @warning: Make sure to suspend the LP ticker first (call ticker_suspend()),
* otherwise the behavior is undefined.
*/
void lp_ticker_wrapper_suspend(void);

Expand Down