RELAY_TIMEOUT_MSEC
unsigned long timeout = msecs_to_jiffies(RELAY_TIMEOUT_MSEC);
busy = ktime_before(now, ktime_add_ms(last_reply, 2 * RELAY_TIMEOUT_MSEC));
msleep(RELAY_TIMEOUT_MSEC / 8);
msleep(RELAY_TIMEOUT_MSEC / 8);