OutputModuleInterface::updateOutputs return bool to control actuator_outputs pub

Required for pwm_out_sim: only publish actuator_outputs when we get
actuator_controls. Otherwise lockstep startup does not work.
The issue was there before but hidden, due to a long poll timeout.

Works with HIL too.

src/drivers/dshot/dshot.cpp

@@ -146,7 +146,7 @@ public:
 					   hrt_abstime edge_time, uint32_t edge_state,
 					   uint32_t overflow);
 
-	void updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+	bool updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 			   unsigned num_outputs, unsigned num_control_groups_updated) override;
 
 	void mixerChanged() override;
@@ -686,11 +686,11 @@ void DShotOutput::mixerChanged()
 	updateTelemetryNumMotors();
 }
 
-void DShotOutput::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+bool DShotOutput::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 				unsigned num_outputs, unsigned num_control_groups_updated)
 {
 	if (!_outputs_on) {
-		return;
+		return false;
 	}
 
 	int requested_telemetry_index = -1;
@@ -740,6 +740,8 @@ void DShotOutput::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS
 	if (stop_motors || num_control_groups_updated > 0) {
 		up_dshot_trigger();
 	}
+
+	return true;
 }
 
 void

src/drivers/pwm_out_sim/PWMSim.cpp

@@ -79,11 +79,13 @@ PWMSim::Run()
 	_mixing_output.updateSubscriptions(true);
 }
 
-void
+bool
 PWMSim::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS], unsigned num_outputs,
 		      unsigned num_control_groups_updated)
 {
-	// nothing to do, as we are only interested in the actuator_outputs topic publication
+	// Nothing to do, as we are only interested in the actuator_outputs topic publication.
+	// That should only be published once we receive actuator_controls (important for lock-step to work correctly)
+	return num_control_groups_updated > 0;
 }
 
 int

src/drivers/pwm_out_sim/PWMSim.hpp

@@ -66,7 +66,7 @@ public:
 
 	int ioctl(device::file_t *filp, int cmd, unsigned long arg) override;
 
-	void updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+	bool updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 			   unsigned num_outputs, unsigned num_control_groups_updated) override;
 
 private:

src/drivers/px4fmu/fmu.cpp

@@ -156,7 +156,7 @@ public:
 
 	void update_pwm_trims();
 
-	void updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+	bool updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 			   unsigned num_outputs, unsigned num_control_groups_updated) override;
 
 private:
@@ -719,11 +719,11 @@ PX4FMU::update_pwm_out_state(bool on)
 }
 
 
-void PX4FMU::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+bool PX4FMU::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 			   unsigned num_outputs, unsigned num_control_groups_updated)
 {
 	if (_test_mode) {
-		return;
+		return false;
 	}
 
 	/* output to the servos */
@@ -739,6 +739,8 @@ void PX4FMU::updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 	if (num_control_groups_updated > 0) {
 		up_pwm_update();
 	}
+
+	return true;
 }
 
 void

src/lib/mixer_module/mixer_module.cpp

@@ -308,9 +308,11 @@ bool MixingOutput::update()
 		unsigned num_motor_test = motorTest();
 
 		if (num_motor_test > 0) {
-			_interface.updateOutputs(false, _current_output_value, num_motor_test, 1);
-			actuator_outputs_s actuator_outputs{};
-			setAndPublishActuatorOutputs(num_motor_test, actuator_outputs);
+			if (_interface.updateOutputs(false, _current_output_value, num_motor_test, 1)) {
+				actuator_outputs_s actuator_outputs{};
+				setAndPublishActuatorOutputs(num_motor_test, actuator_outputs);
+			}
+
 			checkSafetyButton();
 			handleCommands();
 			return true;
@@ -375,14 +377,13 @@ bool MixingOutput::update()
 	reorderOutputs(_current_output_value);
 
 	/* now return the outputs to the driver */
-	_interface.updateOutputs(stop_motors, _current_output_value, mixed_num_outputs, n_updates);
-
+	if (_interface.updateOutputs(stop_motors, _current_output_value, mixed_num_outputs, n_updates)) {
+		actuator_outputs_s actuator_outputs{};
+		setAndPublishActuatorOutputs(mixed_num_outputs, actuator_outputs);
 
-	actuator_outputs_s actuator_outputs{};
-	setAndPublishActuatorOutputs(mixed_num_outputs, actuator_outputs);
-
-	publishMixerStatus(actuator_outputs);
-	updateLatencyPerfCounter(actuator_outputs);
+		publishMixerStatus(actuator_outputs);
+		updateLatencyPerfCounter(actuator_outputs);
+	}
 
 	checkSafetyButton();
 	handleCommands();

src/lib/mixer_module/mixer_module.hpp

@@ -66,7 +66,16 @@ public:
 	OutputModuleInterface(const char *name, const px4::wq_config_t &config)
 		: px4::ScheduledWorkItem(name, config), ModuleParams(nullptr) {}
 
-	virtual void updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
+	/**
+	 * Callback to update the (physical) actuator outputs in the driver
+	 * @param stop_motors if true, all motors must be stopped (if false, individual motors
+	 *                    might still be stopped via outputs[i] == disarmed_value)
+	 * @param outputs individual actuator outputs in range [min, max] or failsafe/disarmed value
+	 * @param num_outputs number of outputs (<= max_num_outputs)
+	 * @param num_control_groups_updated number of actuator_control groups updated
+	 * @return if true, the update got handled, and actuator_outputs can be published
+	 */
+	virtual bool updateOutputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS],
 				   unsigned num_outputs, unsigned num_control_groups_updated) = 0;
 
 	/** called whenever the mixer gets updated/reset */