From c51aabcfec1591a222e5b3d8588616fc47e9ece5 Mon Sep 17 00:00:00 2001
From: Eurus <105340988+AkaiEurus@users.noreply.github.com>
Date: Sat, 4 Jul 2026 05:29:14 +0800
Subject: [PATCH] fix(commander): require GNSS altitude fusion for raw home
 position (#27604)

* HomePosition: require GPS altitude fusion for raw GNSS home

* Commander: name GNSS position fusion mask
---
 src/modules/commander/HomePosition.cpp | 8 ++++----
 src/modules/commander/HomePosition.hpp | 3 ++-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/modules/commander/HomePosition.cpp b/src/modules/commander/HomePosition.cpp
index 4eb0f068de..f092e8a631 100644
--- a/src/modules/commander/HomePosition.cpp
+++ b/src/modules/commander/HomePosition.cpp
@@ -301,17 +301,17 @@ void HomePosition::setHomePosValid()
 	_valid = true;
 }
 
-bool HomePosition::isGpsHorizontalFusionEnabled()
+bool HomePosition::isGpsPositionFusionEnabled()
 {
 	// If parameter doesn't exist, allow GPS usage
 	if (_param_ekf2_gps_ctrl_handle == PARAM_INVALID) {
 		return true;
 	}
 
-	// Check if bit 0 (horizontal position fusion) is set
+	// Raw GNSS home position uses both horizontal position and altitude.
 	int32_t ekf2_gps_ctrl = 0;
 	param_get(_param_ekf2_gps_ctrl_handle, &ekf2_gps_ctrl);
-	return (ekf2_gps_ctrl & 1);
+	return (ekf2_gps_ctrl & kGpsCtrlHorizontalAndAltitude) == kGpsCtrlHorizontalAndAltitude;
 }
 
 void HomePosition::updateHomePositionYaw(float yaw)
@@ -364,7 +364,7 @@ void HomePosition::update(bool set_automatically, bool check_if_changed)
 		const bool evh_valid = vehicle_gps_position.s_variance_m_s < kHomePositionGPSRequiredEVH;
 
 		_gps_position_for_home_valid = time_valid && fix_valid && eph_valid && epv_valid && evh_valid
-					       && isGpsHorizontalFusionEnabled();
+					       && isGpsPositionFusionEnabled();
 
 		if (_param_com_home_en.get() && _gps_position_for_home_valid && _last_gps_timestamp != 0 && _last_baro_timestamp != 0
 		    && _takeoff_time != 0 && now < _takeoff_time + kHomePositionCorrectionTimeWindow) {
diff --git a/src/modules/commander/HomePosition.hpp b/src/modules/commander/HomePosition.hpp
index fd5eb1e72d..bb817548a3 100644
--- a/src/modules/commander/HomePosition.hpp
+++ b/src/modules/commander/HomePosition.hpp
@@ -51,6 +51,7 @@ static constexpr int kHomePositionGPSRequiredFixType = 2;
 static constexpr float kHomePositionGPSRequiredEPH = 5.f;
 static constexpr float kHomePositionGPSRequiredEPV = 10.f;
 static constexpr float kHomePositionGPSRequiredEVH = 1.f;
+static constexpr int32_t kGpsCtrlHorizontalAndAltitude = (1 << 0) | (1 << 1);
 static constexpr float kMinHomePositionChangeEPH = 1.f;
 static constexpr float kMinHomePositionChangeEPV = 1.5f;
 static constexpr float kLpfBaroTimeConst = 5.f;
@@ -74,7 +75,7 @@ public:
 
 private:
 	bool hasMovedFromCurrentHomeLocation();
-	bool isGpsHorizontalFusionEnabled();
+	bool isGpsPositionFusionEnabled();
 	void setHomePosValid();
 	void updateHomePositionYaw(float yaw);