From bc914006bf0d20da3ab2f6b10401ee6d2acfec8e Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Thu, 27 Aug 2026 14:00:33 +1000
Subject: [PATCH] AP_Compass: remove primary compass parameter conversion

Converted the old COMPASS_PRIMARY into the device-id priority list.
Added Feb-2020 and present in the 4.3.0 release, so anybody running
4.3.0 or later has already had it applied.

Note that the conversion sat inside Compass::init(), below its

    if (!_enabled) {
        return;
    }

early return, so "present in the release" is not quite the same as "has
run".  A user who has had COMPASS_ENABLE=0 for every release from 4.3
onwards never reached the conversion, and if they enable the compass
after moving to 4.8 their old COMPASS_PRIMARY selection is not honoured.
That is judged too unlikely - and the parameter too old - to keep the
conversion for.
---
 libraries/AP_Compass/AP_Compass.cpp | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/libraries/AP_Compass/AP_Compass.cpp b/libraries/AP_Compass/AP_Compass.cpp
index 4b971385e1c..71b0ef53648 100644
--- a/libraries/AP_Compass/AP_Compass.cpp
+++ b/libraries/AP_Compass/AP_Compass.cpp
@@ -719,24 +719,6 @@ void Compass::init()
     }
 
 #if COMPASS_MAX_INSTANCES > 1
-    // PARAMETER_CONVERSION - Added: Feb-2020 for ArduPilot-4.0
-    // Look if there was a primary compass setup in previous version
-    // if so and the primary compass is not set in current setup
-    // make the devid as primary.
-    if (_priority_did_stored_list[Priority(0)] == 0) {
-        uint16_t k_param_compass;
-        if (AP_Param::find_top_level_key_by_pointer(this, k_param_compass)) {
-            const AP_Param::ConversionInfo primary_compass_old_param = {k_param_compass, 12, AP_PARAM_INT8, ""};
-            AP_Int8 value;
-            value.set(0);
-            bool primary_param_exists = AP_Param::find_old_parameter(&primary_compass_old_param, &value);
-            int8_t oldvalue = value.get();
-            if ((oldvalue!=0) && (oldvalue<COMPASS_MAX_INSTANCES) && primary_param_exists) {
-                _priority_did_stored_list[Priority(0)].set_and_save_ifchanged(_state[StateIndex(oldvalue)].dev_id);
-            }
-        }
-    }
-
     // Load priority list from storage, the changes to priority list
     // by user only take effect post reboot, after this
     if (!suppress_devid_save) {