commander: remove unused HITL transition function

To my knowledge this hil transition function is not used anymore,
however, it makes sending the DO_SET_MODE command unnecessarily complex.
In my opinion the DO_SET_MODE command should only change the mode but
not other things like arming (already removed) and HITL state (this
commit).

Often times, I was seeing the error message "Set SYS_HITL to 1 and
reboot to enable HITL." when using QGC with a vehicle in HITL.

HITL is set via parameter which then has an impact in the startup script
where the CLI argument `-hil` is added to some of the commands that
require it (like commander as well).

src/modules/commander/Commander.cpp

@@ -593,10 +593,6 @@ Commander::handle_command(vehicle_status_s *status_local, const vehicle_command_
 
 			transition_result_t main_ret = TRANSITION_NOT_CHANGED;
 
-			/* set HIL state */
-			hil_state_t new_hil_state = (base_mode & VEHICLE_MODE_FLAG_HIL_ENABLED) ? vehicle_status_s::HIL_STATE_ON : vehicle_status_s::HIL_STATE_OFF;
-			transition_result_t hil_ret = hil_state_transition(new_hil_state, status_pub, status_local, &mavlink_log_pub);
-
 			// We ignore base_mode & VEHICLE_MODE_FLAG_SAFETY_ARMED because
 			// the command VEHICLE_CMD_COMPONENT_ARM_DISARM should be used
 			// instead according to the latest mavlink spec.
@@ -704,7 +700,7 @@ Commander::handle_command(vehicle_status_s *status_local, const vehicle_command_
 				}
 			}
 
-			if ((hil_ret != TRANSITION_DENIED) && (arming_ret != TRANSITION_DENIED) && (main_ret != TRANSITION_DENIED)) {
+			if ((arming_ret != TRANSITION_DENIED) && (main_ret != TRANSITION_DENIED)) {
 				cmd_result = vehicle_command_s::VEHICLE_CMD_RESULT_ACCEPTED;
 
 			} else {

src/modules/commander/state_machine_helper.cpp

@@ -368,65 +368,6 @@ main_state_transition(const vehicle_status_s &status, const main_state_t new_mai
 	return ret;
 }
 
-/**
- * Transition from one hil state to another
- */
-transition_result_t hil_state_transition(hil_state_t new_state, orb_advert_t status_pub,
-		vehicle_status_s *current_status, orb_advert_t *mavlink_log_pub)
-{
-	transition_result_t ret = TRANSITION_DENIED;
-
-	if (current_status->hil_state == new_state) {
-		ret = TRANSITION_NOT_CHANGED;
-
-	} else {
-		switch (new_state) {
-		case vehicle_status_s::HIL_STATE_OFF:
-			/* The system is in HITL mode and unexpected things can happen if we disable HITL without rebooting. */
-			mavlink_log_critical(mavlink_log_pub, "Set SYS_HITL to 0 and reboot to disable HITL.");
-			ret = TRANSITION_DENIED;
-			break;
-
-		case vehicle_status_s::HIL_STATE_ON:
-			if (current_status->arming_state == vehicle_status_s::ARMING_STATE_INIT
-			    || current_status->arming_state == vehicle_status_s::ARMING_STATE_STANDBY
-			    || current_status->arming_state == vehicle_status_s::ARMING_STATE_STANDBY_ERROR) {
-
-				ret = TRANSITION_CHANGED;
-
-				int32_t hitl_on = 0;
-				param_get(param_find("SYS_HITL"), &hitl_on);
-
-				if (hitl_on) {
-					mavlink_log_info(mavlink_log_pub, "Enabled Hardware-in-the-loop simulation (HITL).");
-
-				} else {
-					mavlink_log_critical(mavlink_log_pub, "Set SYS_HITL to 1 and reboot to enable HITL.");
-					ret = TRANSITION_DENIED;
-				}
-
-			} else {
-				mavlink_log_critical(mavlink_log_pub, "Not switching to HITL when armed.");
-				ret = TRANSITION_DENIED;
-			}
-
-			break;
-
-		default:
-			PX4_WARN("Unknown HITL state");
-			break;
-		}
-	}
-
-	if (ret == TRANSITION_CHANGED) {
-		current_status->hil_state = new_state;
-		current_status->timestamp = hrt_absolute_time();
-		orb_publish(ORB_ID(vehicle_status), status_pub, current_status);
-	}
-
-	return ret;
-}
-
 /**
  * Enable failsafe and report to user
  */

src/modules/commander/state_machine_helper.h

@@ -88,9 +88,6 @@ transition_result_t
 main_state_transition(const vehicle_status_s &status, const main_state_t new_main_state,
 		      const vehicle_status_flags_s &status_flags, commander_state_s *internal_state);
 
-transition_result_t hil_state_transition(hil_state_t new_state, orb_advert_t status_pub,
-		vehicle_status_s *current_status, orb_advert_t *mavlink_log_pub);
-
 void enable_failsafe(vehicle_status_s *status, bool old_failsafe, orb_advert_t *mavlink_log_pub, const char *reason);
 
 bool set_nav_state(vehicle_status_s *status, actuator_armed_s *armed, commander_state_s *internal_state,