HomePosition: only set home position using GNSS if bit 0 in EKF2_GPS_CTRL is active

[mahima-yoga]

Solved Problem

The home position was being set using raw GNSS data even when the vehicle position estimate did not use GNSS. See video:

Screencast.from.01-29-2026.02.29.37.PM.webm

Solution

If the vehicle position is not set by GNSS, then the home position should not be either. The proposed solutions checks whether vehicle horizontal position is using GNSS by checking if bit 0 is enabled in EKF2_GPS_CTRL.

Changelog Entry

For release notes:

Feature/Bugfix only set home position using GNSS if vehicle position also uses GNSS

Test coverage

Tested in SIH (log).

Screencast.from.01-29-2026.01.44.14.PM.webm

[github-actions]

🔎 FLASH Analysis

px4_fmu-v5x [Total VM Diff: 88 byte (0 %)]

    FILE SIZE        VM SIZE    
--------------  -------------- 
+0.0%     +88  +0.0%     +88    .text
  [NEW]     +40  [NEW]     +40    HomePosition::isGpsHorizontalFusionEnabled()
  +0.0%     +24  +0.0%     +24    [section .text]
  +4.4%     +16  +4.4%     +16    HomePosition::HomePosition()
  +0.9%      +8  +0.9%      +8    HomePosition::update()
+0.0%     +49  [ = ]       0    .debug_abbrev
+0.0%      +8  [ = ]       0    .debug_aranges
+0.0%     +28  [ = ]       0    .debug_frame
+0.0%    +277  [ = ]       0    .debug_info
+0.0%     +74  [ = ]       0    .debug_line
 -80.0%      -4  [ = ]       0    [Unmapped]
  +0.0%     +78  [ = ]       0    [section .debug_line]
+0.0%     +17  [ = ]       0    .debug_loclists
+0.0%     +20  [ = ]       0    .debug_rnglists
  [NEW]      +2  [ = ]       0    [Unmapped]
  +0.0%     +18  [ = ]       0    [section .debug_rnglists]
+0.0%    +107  [ = ]       0    .debug_str
+0.8%      +2  [ = ]       0    .shstrtab
+0.0%     +50  [ = ]       0    .strtab
  [NEW]     +50  [ = ]       0    HomePosition::isGpsHorizontalFusionEnabled()
 -40.0%     -16  [ = ]       0    __hrt_call_enter_veneer
  +100%     +16  [ = ]       0    __memset_veneer
+0.0%     +32  [ = ]       0    .symtab
  [NEW]     +32  [ = ]       0    HomePosition::isGpsHorizontalFusionEnabled()
 -40.0%     -32  [ = ]       0    __hrt_call_enter_veneer
   +67%     +32  [ = ]       0    __memset_veneer
 -25.0%     -16  [ = ]       0    __nxsem_restore_baseprio_irq_veneer
   +50%     +16  [ = ]       0    __nxsig_pendingset_veneer
   +33%     +16  [ = ]       0    __pthread_mutex_lock_veneer
 -33.3%     -16  [ = ]       0    __uart_recvchars_veneer
-1.0%     -88  [ = ]       0    [Unmapped]
+0.0%    +664  +0.0%     +88    TOTAL

px4_fmu-v6x [Total VM Diff: 88 byte (0 %)]

    FILE SIZE        VM SIZE    
--------------  -------------- 
+0.0%     +88  +0.0%     +88    .text
  [NEW]     +40  [NEW]     +40    HomePosition::isGpsHorizontalFusionEnabled()
  +0.0%     +20  +0.0%     +20    [section .text]
  +4.4%     +16  +4.4%     +16    HomePosition::HomePosition()
  +0.9%      +8  +0.9%      +8    HomePosition::update()
   +44%      +4   +44%      +4    g_nullstring
+0.0%     +49  [ = ]       0    .debug_abbrev
+0.0%      +8  [ = ]       0    .debug_aranges
+0.0%     +28  [ = ]       0    .debug_frame
+0.0%    +277  [ = ]       0    .debug_info
+0.0%     +82  [ = ]       0    .debug_line
  +133%      +4  [ = ]       0    [Unmapped]
  +0.0%     +78  [ = ]       0    [section .debug_line]
+0.0%     +17  [ = ]       0    .debug_loclists
+0.0%     +20  [ = ]       0    .debug_rnglists
  [NEW]      +2  [ = ]       0    [Unmapped]
  +0.0%     +18  [ = ]       0    [section .debug_rnglists]
+0.0%    +107  [ = ]       0    .debug_str
-0.8%      -2  [ = ]       0    .shstrtab
+0.0%     +50  [ = ]       0    .strtab
  [NEW]     +50  [ = ]       0    HomePosition::isGpsHorizontalFusionEnabled()
+0.0%     +32  [ = ]       0    .symtab
  [NEW]     +32  [ = ]       0    HomePosition::isGpsHorizontalFusionEnabled()
-1.3%     -88  [ = ]       0    [Unmapped]
+0.0%    +668  +0.0%     +88    TOTAL

Updated: 2026-01-30T09:41:22

[sfuhrer]

Nice, looks clean.