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Fix double low power ticker interrupt #7599

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Merged
merged 1 commit into from
Aug 20, 2018
Merged

Fix double low power ticker interrupt #7599

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21 changes: 9 additions & 12 deletions hal/mbed_ticker_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -164,9 +164,9 @@ static void update_present_time(const ticker_data_t *const ticker)
}

/**
* Given the absolute timestamp compute the hal tick timestamp.
* Given the absolute timestamp compute the hal tick timestamp rounded up.
*/
static timestamp_t compute_tick(const ticker_data_t *const ticker, us_timestamp_t timestamp)
static timestamp_t compute_tick_round_up(const ticker_data_t *const ticker, us_timestamp_t timestamp)
{
ticker_event_queue_t *queue = ticker->queue;
us_timestamp_t delta_us = timestamp - queue->present_time;
Expand All @@ -185,14 +185,14 @@ static timestamp_t compute_tick(const ticker_data_t *const ticker, us_timestamp_
} else if (0 != queue->frequency_shifts) {
// Optimized frequencies divisible by 2

delta = (delta_us << ticker->queue->frequency_shifts) / 1000000;
delta = ((delta_us << ticker->queue->frequency_shifts) + 1000000 - 1) / 1000000;
if (delta > ticker->queue->max_delta) {
delta = ticker->queue->max_delta;
}
} else {
// General case

delta = delta_us * queue->frequency / 1000000;
delta = (delta_us * queue->frequency + 1000000 - 1) / 1000000;
if (delta > ticker->queue->max_delta) {
delta = ticker->queue->max_delta;
}
Expand Down Expand Up @@ -242,14 +242,11 @@ static void schedule_interrupt(const ticker_data_t *const ticker)
return;
}

timestamp_t match_tick = compute_tick(ticker, match_time);
// The time has been checked to be future, but it could still round
// to the last tick as a result of us to ticks conversion
if (match_tick == queue->tick_last_read) {
// Match time has already expired so fire immediately
ticker->interface->fire_interrupt();
return;
}
timestamp_t match_tick = compute_tick_round_up(ticker, match_time);

// The same tick should never occur since match_tick is rounded up.
// If the same tick is returned scheduling will not work correctly.
MBED_ASSERT(match_tick != queue->tick_last_read);

ticker->interface->set_interrupt(match_tick);
timestamp_t cur_tick = ticker->interface->read();
Expand Down