Fix nrf::rtc errata workaround (#858)

* Deprecate `should_dequeue_check`

* Fix errata by delaying the wakeup point

* Add changelog

* Fix changelog typos

rtic-time/CHANGELOG.md

@@ -12,6 +12,7 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 ### Changed
 
 - Docs: Add sanity check to `half_period_counter` code example
+- Deprecate `Monotonic::should_dequeue_check` as it was erroneous
 
 ### Fixed
 

rtic-time/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rtic-time"
-version = "1.1.0"
+version = "1.2.0"
 
 edition = "2021"
 authors = [

rtic-time/src/lib.rs

@@ -133,7 +133,7 @@ impl<Mono: Monotonic> TimerQueue<Mono> {
             let head = self.queue.pop_if(|head| {
                 release_at = Some(head.release_at);
 
-                let should_pop = Mono::should_dequeue_check(head.release_at);
+                let should_pop = Mono::now() >= head.release_at;
                 head.was_popped.store(should_pop, Ordering::Relaxed);
 
                 should_pop
@@ -147,7 +147,7 @@ impl<Mono: Monotonic> TimerQueue<Mono> {
                     Mono::enable_timer();
                     Mono::set_compare(instant);
 
-                    if Mono::should_dequeue_check(instant) {
+                    if Mono::now() >= instant {
                         // The time for the next instant passed while handling it,
                         // continue dequeueing
                         continue;

rtic-time/src/monotonic.rs

@@ -36,11 +36,15 @@ pub trait Monotonic {
     /// queue in RTIC checks this.
     fn set_compare(instant: Self::Instant);
 
-    /// Override for the dequeue check, override with timers that have bugs.
-    ///
-    /// E.g. nRF52 RTCs needs to be dequeued if the time is within 4 ticks.
-    fn should_dequeue_check(release_at: Self::Instant) -> bool {
-        <Self as Monotonic>::now() >= release_at
+    /// This method used to be required by an errata workaround
+    /// for the nrf52 family, but it has been disabled as the
+    /// workaround was erroneous.
+    #[deprecated(
+        since = "1.2.0",
+        note = "this method is erroneous and has been disabled"
+    )]
+    fn should_dequeue_check(_: Self::Instant) -> bool {
+        panic!("This method should not be used as it is erroneous.")
     }
 
     /// Clear the compare interrupt flag.