libcamera: timer: Allow restarting a timer before expiration

The Timer API allows restarting a timer before expiration. This isn't
correctly implemented, fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/timer.cpp

@@ -75,6 +75,9 @@ void Timer::start(std::chrono::milliseconds duration)
 		<< duration.count() << ": deadline "
 		<< utils::time_point_to_string(deadline_);
 
+	if (isRunning())
+		unregisterTimer();
+
 	registerTimer();
 }
 
@@ -88,6 +91,9 @@ void Timer::start(std::chrono::milliseconds duration)
  */
 void Timer::stop()
 {
+	if (!isRunning())
+		return;
+
 	unregisterTimer();
 }