ledc: bugfix - Simplify the procedure to perform a one-time duty update

Avoid adding one extra fade cycle when performing a one-time duty update.
Add some notes to ledc_get_duty and ledc_update_duty APIs, so that users
are aware of when the new duty will be effective.

Closes https://github.com/espressif/esp-idf/issues/7288

(cherry picked from commit e175086226405ca5dfd0b0cdde917b0ad8330827)

components/driver/include/driver/ledc.h

@@ -85,6 +85,7 @@ esp_err_t ledc_timer_config(const ledc_timer_config_t* timer_conf);
  * @brief LEDC update channel parameters
  * @note  Call this function to activate the LEDC updated parameters.
  *        After ledc_set_duty, we need to call this function to update the settings.
+ *        And the new LEDC parameters don't take effect until the next PWM cycle.
  * @note  ledc_set_duty, ledc_set_duty_with_hpoint and ledc_update_duty are not thread-safe, do not call these functions to
  *        control one LEDC channel in different tasks at the same time.
  *        A thread-safe version of API is ledc_set_duty_and_update
@@ -203,6 +204,9 @@ esp_err_t ledc_set_duty(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t
 
 /**
  * @brief LEDC get duty
+ *        This function returns the duty at the present PWM cycle.
+ *        You shouldn't expect the function to return the new duty in the same cycle of calling ledc_update_duty,
+ *        because duty update doesn't take effect until the next cycle.
  *
  * @param speed_mode Select the LEDC channel group with specified speed mode. Note that not all targets support high speed mode.
  * @param channel LEDC channel (0 - LEDC_CHANNEL_MAX-1), select from ledc_channel_t

components/driver/ledc.c

@@ -466,8 +466,8 @@ esp_err_t ledc_set_duty_with_hpoint(ledc_mode_t speed_mode, ledc_channel_t chann
                      hpoint,          //uint32_t hpoint_val,
                      duty,           //uint32_t duty_val,
                      1,               //uint32_t increase,
-                     1,               //uint32_t duty_num,
-                     1,               //uint32_t duty_cycle,
+                     0,               //uint32_t duty_num,
+                     0,               //uint32_t duty_cycle,
                      0                //uint32_t duty_scale
                      );
     _ledc_fade_hw_release(speed_mode, channel);
@@ -486,8 +486,8 @@ esp_err_t ledc_set_duty(ledc_mode_t speed_mode, ledc_channel_t channel, uint32_t
                      LEDC_VAL_NO_CHANGE,
                      duty,           //uint32_t duty_val,
                      1,               //uint32_t increase,
-                     1,               //uint32_t duty_num,
-                     1,               //uint32_t duty_cycle,
+                     0,               //uint32_t duty_num,
+                     0,               //uint32_t duty_cycle,
                      0                //uint32_t duty_scale
                      );
     _ledc_fade_hw_release(speed_mode, channel);
@@ -855,12 +855,13 @@ esp_err_t ledc_set_duty_and_update(ledc_mode_t speed_mode, ledc_channel_t channe
     LEDC_ARG_CHECK(speed_mode < LEDC_SPEED_MODE_MAX, "speed_mode");
     LEDC_ARG_CHECK(channel < LEDC_CHANNEL_MAX, "channel");
     LEDC_ARG_CHECK(duty <= ledc_get_max_duty(speed_mode, channel), "target_duty");
+    LEDC_ARG_CHECK(hpoint <= LEDC_HPOINT_VAL_MAX, "hpoint");
     LEDC_CHECK(p_ledc_obj[speed_mode] != NULL, LEDC_NOT_INIT, ESP_ERR_INVALID_STATE);
     LEDC_CHECK(ledc_fade_channel_init_check(speed_mode, channel) == ESP_OK , LEDC_FADE_INIT_ERROR_STR, ESP_FAIL);
     _ledc_op_lock_acquire(speed_mode, channel);
     _ledc_fade_hw_acquire(speed_mode, channel);
-    _ledc_set_fade_with_step(speed_mode, channel, duty, 0, 1);
-    _ledc_fade_start(speed_mode, channel, LEDC_FADE_WAIT_DONE);
+    ledc_duty_config(speed_mode, channel, hpoint, duty, 1, 0, 0, 0);
+    ledc_update_duty(speed_mode, channel);
     _ledc_fade_hw_release(speed_mode, channel);
     _ledc_op_lock_release(speed_mode, channel);
     return ESP_OK;