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Merge branch 'fix/usleep_returns_early' into 'master'

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fix(newlib): Fixed an issue where usleep() could consume more CPU cycles

Closes IDFGH-14342

See merge request espressif/esp-idf!38812
This commit is contained in:
Sudeep Mohanty
2025-05-09 17:18:25 +08:00
parent 5cf9278bb3 1e616eeb84
commit 196bd4368a
2 changed files with 8 additions and 7 deletions
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2
components/driver/test_apps/legacy_mcpwm_driver/main/test_legacy_mcpwm.c
View File

@ -172,7 +172,7 @@ static uint32_t pcnt_get_pulse_number(pcnt_unit_handle_t pwm_pcnt_unit, int capt
int count_value = 0;
TEST_ESP_OK(pcnt_unit_clear_count(pwm_pcnt_unit));
TEST_ESP_OK(pcnt_unit_start(pwm_pcnt_unit));
usleep(capture_window_ms * 1000);
vTaskDelay(pdMS_TO_TICKS(capture_window_ms));
TEST_ESP_OK(pcnt_unit_stop(pwm_pcnt_unit));
TEST_ESP_OK(pcnt_unit_get_count(pwm_pcnt_unit, &count_value));
printf("count value: %d\r\n", count_value);

13
components/newlib/src/time.c
View File

@ -219,12 +219,13 @@ int usleep(useconds_t us)
do {
vTaskDelay((((target_us - now_us) + us_per_tick - 1) / us_per_tick));
now_us = esp_time_impl_get_time();
/* If the time left until the target is less than 1 tick, then we use ROM delay to fill the gap */
uint64_t time_left = target_us - now_us;
if (time_left != 0 && time_left < us_per_tick) {
esp_rom_delay_us(time_left);
break;
}
/* It is possible that the time left until the target time is less
* than a tick period. However, we let usleep() to sleep for an
* entire tick period. This, could result in usleep() sleeping for
* a longer time than the requested time but that does not violate
* the spec of usleep(). Additionally, it allows FreeRTOS to schedule
* other tasks while the current task is sleeping.
*/
} while (now_us < target_us);
}
return 0;