Pwm2 does not work

#1

On rock-3a, pwm2 does not work, what could be the reason?

follow these steps:

  1. append “dtoverlay=rk3568-pwm2-m0” to /boot/config.txt
  2. Execute “sudo update_extlinux.sh”
  3. Restart the device
  4. Run the following code, but I can’t get PWM on pwm2-m0 (pin22) 
    #define PWM 22

mraa_pwm_context pwm;
pwm = mraa_pwm_init(PWM);
mraa_pwm_period_us(pwm, 2);
mraa_pwm_enable(pwm, 1);
mraa_pwm_write(pwm, 0.5);