+ /*
+ * Set polarity.
+ *
+ * The PWM starts in inactive state until the internal timer reaches the
+ * duty value, then becomes active until the timer reaches the period
+ * value. In theory, we should then use (period - duty) as the real duty
+ * value, as a high duty value would otherwise result in the PWM pin
+ * being inactive most of the time.
+ *
+ * Here, we don't do that, and instead invert the polarity of the PWM
+ * when it is active. This trick makes the PWM start with its active
+ * state instead of its inactive state.
+ */
+ if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)