[NUC472/M453] Remove fix of lp_ticker wrap-around

The original fix cannot handle both wrap-around and scheduled alarm behind now well.
Leave wrap-around as known issue.

Author: ccli8

targets/TARGET_NUVOTON/TARGET_M451/lp_ticker.c

@@ -147,7 +147,14 @@ void lp_ticker_set_interrupt(timestamp_t timestamp)
 
     TIMER_Stop((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
 
-    int delta = (timestamp > now) ? (timestamp - now) : (uint32_t) ((uint64_t) timestamp + 0xFFFFFFFFu - now);
+    /**
+     * FIXME: Scheduled alarm may go off incorrectly due to wrap around.
+     * Conditions in which delta is negative:
+     * 1. Wrap around
+     * 2. Newly scheduled alarm is behind now
+     */ 
+    //int delta = (timestamp > now) ? (timestamp - now) : (uint32_t) ((uint64_t) timestamp + 0xFFFFFFFFu - now);
+    int delta = (int) (timestamp - now);
     if (delta > 0) {
         cd_major_minor_clks = (uint64_t) delta * US_PER_TICK * TMR3_CLK_PER_SEC / US_PER_SEC;
         lp_ticker_arm_cd();

targets/TARGET_NUVOTON/TARGET_NUC472/lp_ticker.c

@@ -146,7 +146,14 @@ void lp_ticker_set_interrupt(timestamp_t timestamp)
 
     TIMER_Stop((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
 
-    int delta = (timestamp > now) ? (timestamp - now) : (uint32_t) ((uint64_t) timestamp + 0xFFFFFFFFu - now);
+    /**
+     * FIXME: Scheduled alarm may go off incorrectly due to wrap around.
+     * Conditions in which delta is negative:
+     * 1. Wrap around
+     * 2. Newly scheduled alarm is behind now
+     */ 
+    //int delta = (timestamp > now) ? (timestamp - now) : (uint32_t) ((uint64_t) timestamp + 0xFFFFFFFFu - now);
+    int delta = (int) (timestamp - now);
     if (delta > 0) {
         cd_major_minor_clks = (uint64_t) delta * US_PER_TICK * TMR3_CLK_PER_SEC / US_PER_SEC;
         lp_ticker_arm_cd();