Why do we have to specify hrtimer_mode twice using hrtimers

Hi All, Why do we need to specify hrtimer_mode twice while using hrtimers. 1. Timer Initialization: void hrtimer_init(struct hrtimer *timer, clockid_t which_clock, enum hrtimer_mode mode); 2. Starting a timer: void hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode); What will happen if i specify different modes in both functions.