driver: nrf_rtc_timer: Remove unnecessary setting of comparator

Remove a piece of code that was supposed to bring an extra update
of the anchor value but which in fact was not able to provide it,
because of the target time checking performed in process_channel(),
and which is anyway unnecessary because the timeout span is limited
to MAX_CYCLES in sys_clock_set_timeout(), so the timeout handler is
guaranteed to be executed at least twice per each RTC overflow.

Signed-off-by: Andrzej Głąbek <[email protected]>

Author: anangl

drivers/timer/nrf_rtc_timer.c

@@ -66,11 +66,6 @@ static void set_comparator(int32_t chan, uint32_t cyc)
 	nrf_rtc_cc_set(RTC, chan, cyc & COUNTER_MAX);
 }
 
-static uint32_t get_comparator(int32_t chan)
-{
-	return nrf_rtc_cc_get(RTC, chan);
-}
-
 static bool event_check(int32_t chan)
 {
 	return nrf_rtc_event_check(RTC, RTC_CHANNEL_EVENT_ADDR(chan));
@@ -387,7 +382,7 @@ static inline bool in_anchor_range(uint32_t cc_value)
 	return (cc_value >= ANCHOR_RANGE_START) && (cc_value < ANCHOR_RANGE_END);
 }
 
-static inline bool anchor_update(uint32_t cc_value)
+static inline void anchor_update(uint32_t cc_value)
 {
 	/* Update anchor when far from overflow */
 	if (in_anchor_range(cc_value)) {
@@ -397,10 +392,7 @@ static inline bool anchor_update(uint32_t cc_value)
 		 * `z_nrf_rtc_timer_read`.
 		 */
 		anchor = (((uint64_t)overflow_cnt) << COUNTER_BIT_WIDTH) + cc_value;
-		return true;
 	}
-
-	return false;
 }
 
 static void sys_clock_timeout_handler(int32_t chan,
@@ -412,7 +404,7 @@ static void sys_clock_timeout_handler(int32_t chan,
 
 	last_count += dticks * CYC_PER_TICK;
 
-	bool anchor_updated = anchor_update(cc_value);
+	anchor_update(cc_value);
 
 	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
 		/* protection is not needed because we are in the RTC interrupt
@@ -424,19 +416,6 @@ static void sys_clock_timeout_handler(int32_t chan,
 
 	sys_clock_announce(IS_ENABLED(CONFIG_TICKLESS_KERNEL) ?
 			   (int32_t)dticks : (dticks > 0));
-
-	if (cc_value == get_comparator(chan)) {
-		/* New value was not set. Set something that can update anchor.
-		 * If anchor was updated we can enable same CC value to trigger
-		 * interrupt after full cycle. Else set event in anchor update
-		 * range. Since anchor was not updated we know that it's very
-		 * far from mid point so setting is done without any protection.
-		 */
-		if (!anchor_updated) {
-			set_comparator(chan, COUNTER_HALF_SPAN);
-		}
-		event_enable(chan);
-	}
 }
 
 static bool channel_processing_check_and_clear(int32_t chan)
@@ -627,6 +606,8 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
 
 	/* Due to elapsed time the calculation above might produce a
 	 * duration that laps the counter.  Don't let it.
+	 * This limitation also guarantees that the anchor will be properly
+	 * updated before every overflow (see anchor_update()).
 	 */
 	if (cyc > MAX_CYCLES) {
 		cyc = MAX_CYCLES;