XIAO ESP32C6: running PWM_blinky example flags calibration issues

[Gerriko]

I attempted to test the PWM_blink example on a XIAO ESP32C6 board.

To get it to work, I created the following overlay (xiao_esp32c6_hpcore.overlay):

/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * Copyright (c) 2023 Espressif Systems (Shanghai) Co., Ltd.
 */

#include <zephyr/dt-bindings/pwm/pwm.h>

/ {
	aliases {
		pwm-0 = &ledc0;
		pwm-led0 = &pwm_led_blue;
	};

	pwmleds {
		compatible = "pwm-leds";
		pwm_led_blue: pwm_led_gpio0_15 {
			label = "PWM LED0";
			pwms = <&ledc0 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
	};
};

&pinctrl {
	ledc0_default: ledc0_default {
		group1 {
			pinmux = <LEDC_CH0_GPIO15>;
			output-enable;
		};
	};
};

&ledc0 {
	pinctrl-0 = <&ledc0_default>;
	pinctrl-names = "default";
	status = "okay";
	#address-cells = <1>;
	#size-cells = <0>;
	channel0@0 {
		reg = <0x0>;
		timer = <0>;
	};
};

I noticed the following additional messages being generated through the serial monitor: "esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed"

Is there any way to use a low freq clock and adjust the prescaler to handle longer time periods?

Using period 31250000
E (16559) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:03.296,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=610, resolution=20

Using period 62500000
E (17403) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:08.140,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=1220, resolution=20

Using period 125000000
E (18246) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:12.984,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=2441, resolution=20

Using period 250000000
E (19089) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:17.828,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=4882, resolution=20

Using period 500000000
E (19932) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:22.672,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=9765, resolution=20

Using period 1000000000
E (20776) esp_clk_tree: esp_clk_tree_src_get_freq_hz(61): freq shouldn't be 0, calibration failed
[00:06:27.516,000] pwm_ledc_esp32: pwm_led_esp32_timer_set: channel_num=0, speed_mode=0, timer_num=0, clock_src=8, prescaler=4882, resolution=20