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esp_timer/esp32: Fix case when alarm_reg > counter_reg but FRC_TIMER_INT_STATUS is not set

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Closes: WIFI-1576
Closes: https://github.com/espressif/esp-idf/issues/2954
This commit is contained in:
KonstantinKondrashov 2020-01-13 14:36:38 +08:00 committed by bot
parent f972606763
commit 2718fdbd95
2 changed files with 40 additions and 3 deletions
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33
components/esp32/esp_timer_esp32.c
View file

@ -216,10 +216,14 @@ void IRAM_ATTR esp_timer_impl_set_alarm(uint64_t timestamp)
// Note that if by the time we update ALARM_REG, COUNT_REG value is higher,
// interrupt will not happen for another ALARM_OVERFLOW_VAL timer ticks,
// so need to check if alarm value is too close in the future (e.g. <2 us away).
const int32_t offset = s_timer_ticks_per_us * 2;
int32_t offset = s_timer_ticks_per_us * 2;
do {
// Adjust current time if overflow has happened
if (timer_overflow_happened()) {
if (timer_overflow_happened() ||
((REG_READ(FRC_TIMER_COUNT_REG(1)) > ALARM_OVERFLOW_VAL) &&
((REG_READ(FRC_TIMER_CTRL_REG(1)) & FRC_TIMER_INT_STATUS) == 0))) {
// 1. timer_overflow_happened() checks overflow with the interrupt flag.
// 2. During several loops, the counter can be higher than the alarm and even step over ALARM_OVERFLOW_VAL boundary (the interrupt flag is not set).
timer_count_reload();
s_time_base_us += s_timer_us_per_overflow;
}
@ -236,7 +240,19 @@ void IRAM_ATTR esp_timer_impl_set_alarm(uint64_t timestamp)
alarm_reg_val = (uint32_t) compare_val;
}
REG_WRITE(FRC_TIMER_ALARM_REG(1), alarm_reg_val);
} while (REG_READ(FRC_TIMER_ALARM_REG(1)) <= REG_READ(FRC_TIMER_COUNT_REG(1)));
int64_t delta = (int64_t)alarm_reg_val - (int64_t)REG_READ(FRC_TIMER_COUNT_REG(1));
if (delta <= 0) {
/*
When the timestamp is a bit less than the current counter then the alarm = current_counter + offset.
But due to CPU_freq in some case can be equal APB_freq the offset time can not exceed the overhead
(the alarm will be less than the counter) and it leads to the infinity loop.
To exclude this behavior to the offset was added the delta to have the opportunity to go through it.
*/
offset += abs((int)delta) + s_timer_ticks_per_us * 2;
} else {
break;
}
} while (1);
portEXIT_CRITICAL(&s_time_update_lock);
}
@ -254,6 +270,17 @@ static void IRAM_ATTR timer_alarm_isr(void *arg)
// Set alarm to the next overflow moment. Later, upper layer function may
// call esp_timer_impl_set_alarm to change this to an earlier value.
REG_WRITE(FRC_TIMER_ALARM_REG(1), ALARM_OVERFLOW_VAL);
if ((REG_READ(FRC_TIMER_COUNT_REG(1)) > ALARM_OVERFLOW_VAL) &&
((REG_READ(FRC_TIMER_CTRL_REG(1)) & FRC_TIMER_INT_STATUS) == 0)) {
/*
This check excludes the case when the alarm can be less than the counter.
Without this check, it is possible because DPORT uses 4-lvl, and users can use the 5 Hi-interrupt,
they can interrupt this function between FRC_TIMER_INT_CLR and setting the alarm = ALARM_OVERFLOW_VAL
that lead to the counter will go ahead leaving the alarm behind.
*/
timer_count_reload();
s_time_base_us += s_timer_us_per_overflow;
}
portEXIT_CRITICAL_ISR(&s_time_update_lock);
// Call the upper layer handler
(*s_alarm_handler)(arg);

10
components/esp32/test/test_esp_timer.c
View file

@ -798,3 +798,13 @@ TEST_CASE("Test case when esp_timer_impl_set_alarm needs set timer < now_time",
printf("alarm_reg = 0x%x, count_reg 0x%x\n", alarm_reg, count_reg);
TEST_ASSERT(alarm_reg <= (count_reg + offset));
}
TEST_CASE("Test esp_timer_impl_set_alarm when the counter is near an overflow value", "[esp_timer]")
{
for (int i = 0; i < 1024; ++i) {
uint32_t count_reg = 0xeffffe00 + i;
REG_WRITE(FRC_TIMER_LOAD_REG(1), count_reg);
printf("%d) count_reg = 0x%x\n", i, count_reg);
esp_timer_impl_set_alarm(1); // timestamp is expired
}
}