diff --git a/Makefile b/Makefile
index 88e58ac03..545e70fcb 100644
--- a/Makefile
+++ b/Makefile
@@ -239,8 +239,7 @@ CC_NO_OPTIMISATION      :=
 #
 # Added after GCC version update, remove once the warnings have been fixed
 #
-TEMPORARY_FLAGS := -Wno-cast-function-type \
-              -Wno-address-of-packed-member \
+TEMPORARY_FLAGS := -Wno-address-of-packed-member \
               -Wno-absolute-value
 
 CFLAGS     += $(ARCH_FLAGS) \
diff --git a/src/main/cms/cms.c b/src/main/cms/cms.c
index d15d141a4..a70838d71 100644
--- a/src/main/cms/cms.c
+++ b/src/main/cms/cms.c
@@ -94,6 +94,8 @@ static int cmsCurrentDevice = -1;
 static unsigned int osdProfileCursor = 1;
 #endif
 
+int menuChainBack;
+
 bool cmsDisplayPortRegister(displayPort_t *pDisplay)
 {
     if (cmsDeviceCount == CMS_MAX_DEVICE)
@@ -400,7 +402,7 @@ static int cmsDrawMenuEntry(displayPort_t *pDisplay, const OSD_Entry *p, uint8_t
 
                 // Special case of sub menu entry with optional value display.
 
-                char *str = ((CMSMenuOptFuncPtr)p->func)();
+                const char *str = p->func(pDisplay, p->data);
                 strncpy(buff, str, CMS_DRAW_BUFFER_LEN);
             } else if (p->type == OME_Funcall && p->data) {
                 strncpy(buff, p->data, CMS_DRAW_BUFFER_LEN);
@@ -537,7 +539,35 @@ static int cmsDrawMenuEntry(displayPort_t *pDisplay, const OSD_Entry *p, uint8_t
     return cnt;
 }
 
-STATIC_UNIT_TESTED long cmsMenuBack(displayPort_t *pDisplay); // Forward; will be resolved after merging
+static void cmsMenuCountPage(displayPort_t *pDisplay)
+{
+    UNUSED(pDisplay);
+    const OSD_Entry *p;
+    for (p = currentCtx.menu->entries; p->type != OME_END; p++);
+    pageCount = (p - currentCtx.menu->entries - 1) / maxMenuItems + 1;
+}
+
+STATIC_UNIT_TESTED const void *cmsMenuBack(displayPort_t *pDisplay)
+{
+    // Let onExit function decide whether to allow exit or not.
+
+    if (currentCtx.menu->onExit) {
+        return currentCtx.menu->onExit(pageTop + currentCtx.cursorRow);
+    }
+
+    if (!menuStackIdx) {
+        return NULL;
+    }
+
+    currentCtx = menuStack[--menuStackIdx];
+
+    cmsMenuCountPage(pDisplay);
+    cmsPageSelect(pDisplay, currentCtx.page);
+
+    cmsPageDebug();
+
+    return NULL;
+}
 
 static void cmsDrawMenu(displayPort_t *pDisplay, uint32_t currentTimeUs)
 {
@@ -600,7 +630,7 @@ static void cmsDrawMenu(displayPort_t *pDisplay, uint32_t currentTimeUs)
     }
 
     if (currentCtx.menu->onDisplayUpdate) {
-        long result = currentCtx.menu->onDisplayUpdate(pageTop + currentCtx.cursorRow);
+        const void *result = currentCtx.menu->onDisplayUpdate(pageTop + currentCtx.cursorRow);
         if (result == MENU_CHAIN_BACK) {
             cmsMenuBack(pDisplay);
 
@@ -634,20 +664,12 @@ static void cmsDrawMenu(displayPort_t *pDisplay, uint32_t currentTimeUs)
     }
 }
 
-static void cmsMenuCountPage(displayPort_t *pDisplay)
-{
-    UNUSED(pDisplay);
-    const OSD_Entry *p;
-    for (p = currentCtx.menu->entries; p->type != OME_END; p++);
-    pageCount = (p - currentCtx.menu->entries - 1) / maxMenuItems + 1;
-}
-
-long cmsMenuChange(displayPort_t *pDisplay, const void *ptr)
+const void *cmsMenuChange(displayPort_t *pDisplay, const void *ptr)
 {
     const CMS_Menu *pMenu = (const CMS_Menu *)ptr;
 
     if (!pMenu) {
-        return 0;
+        return NULL;
     }
 
 #ifdef CMS_MENU_DEBUG
@@ -666,7 +688,7 @@ long cmsMenuChange(displayPort_t *pDisplay, const void *ptr)
         // Stack the current menu and move to a new menu.
         if (menuStackIdx >= CMS_MENU_STACK_LIMIT - 1) {
             // menu stack limit reached - prevent array overflow
-            return 0;
+            return NULL;
         }
 
         menuStack[menuStackIdx++] = currentCtx;
@@ -675,7 +697,7 @@ long cmsMenuChange(displayPort_t *pDisplay, const void *ptr)
         currentCtx.cursorRow = 0;
 
         if (pMenu->onEnter) {
-            long result = pMenu->onEnter();
+            const void *result = pMenu->onEnter();
             if (result == MENU_CHAIN_BACK) {
                 return cmsMenuBack(pDisplay);
             }
@@ -695,32 +717,7 @@ long cmsMenuChange(displayPort_t *pDisplay, const void *ptr)
 
     cmsPageDebug();
 
-    return 0;
-}
-
-STATIC_UNIT_TESTED long cmsMenuBack(displayPort_t *pDisplay)
-{
-    // Let onExit function decide whether to allow exit or not.
-
-    if (currentCtx.menu->onExit) {
-        long result = currentCtx.menu->onExit(pageTop + currentCtx.cursorRow);
-        if (result < 0) {
-            return MENU_CHAIN_BACK;
-        }
-    }
-
-    if (!menuStackIdx) {
-        return 0;
-    }
-
-    currentCtx = menuStack[--menuStackIdx];
-
-    cmsMenuCountPage(pDisplay);
-    cmsPageSelect(pDisplay, currentCtx.page);
-
-    cmsPageDebug();
-
-    return 0;
+    return NULL;
 }
 
 void cmsMenuOpen(void)
@@ -788,7 +785,7 @@ static void cmsTraverseGlobalExit(const CMS_Menu *pMenu)
 
 }
 
-long cmsMenuExit(displayPort_t *pDisplay, const void *ptr)
+const void *cmsMenuExit(displayPort_t *pDisplay, const void *ptr)
 {
     int exitType = (int)ptr;
     switch (exitType) {
@@ -839,7 +836,7 @@ long cmsMenuExit(displayPort_t *pDisplay, const void *ptr)
 
     unsetArmingDisabled(ARMING_DISABLED_CMS_MENU);
 
-    return 0;
+    return NULL;
 }
 
 // Stick/key detection and key codes
@@ -923,7 +920,7 @@ STATIC_UNIT_TESTED uint16_t cmsHandleKey(displayPort_t *pDisplay, cms_key_e key)
             break;
 
         case OME_Funcall:;
-            long retval;
+            const void *retval;
             if (p->func && key == CMS_KEY_RIGHT) {
                 retval = p->func(pDisplay, p->data);
                 if (retval == MENU_CHAIN_BACK) {
diff --git a/src/main/cms/cms.h b/src/main/cms/cms.h
index aea6b1261..ec1a3bcfc 100644
--- a/src/main/cms/cms.h
+++ b/src/main/cms/cms.h
@@ -48,8 +48,8 @@ void cmsHandler(timeUs_t currentTimeUs);
 
 bool cmsDisplayPortSelect(displayPort_t *instance);
 void cmsMenuOpen(void);
-long cmsMenuChange(displayPort_t *pPort, const void *ptr);
-long cmsMenuExit(displayPort_t *pPort, const void *ptr);
+const void *cmsMenuChange(displayPort_t *pPort, const void *ptr);
+const void *cmsMenuExit(displayPort_t *pPort, const void *ptr);
 void cmsSetExternKey(cms_key_e extKey);
 
 #define CMS_STARTUP_HELP_TEXT1 "MENU:THR MID"
diff --git a/src/main/cms/cms_menu_blackbox.c b/src/main/cms/cms_menu_blackbox.c
index dfab27f27..f3153b7e3 100644
--- a/src/main/cms/cms_menu_blackbox.c
+++ b/src/main/cms/cms_menu_blackbox.c
@@ -148,12 +148,12 @@ static void cmsx_Blackbox_GetDeviceStatus(void)
 }
 
 #ifdef USE_FLASHFS
-static long cmsx_EraseFlash(displayPort_t *pDisplay, const void *ptr)
+static const void *cmsx_EraseFlash(displayPort_t *pDisplay, const void *ptr)
 {
     UNUSED(ptr);
 
     if (!flashfsIsSupported()) {
-        return 0;
+        return NULL;
     }
 
     displayClearScreen(pDisplay);
@@ -172,20 +172,20 @@ static long cmsx_EraseFlash(displayPort_t *pDisplay, const void *ptr)
     // Update storage device status to show new used space amount
     cmsx_Blackbox_GetDeviceStatus();
 
-    return 0;
+    return NULL;
 }
 #endif // USE_FLASHFS
 
-static long cmsx_Blackbox_onEnter(void)
+static const void *cmsx_Blackbox_onEnter(void)
 {
     cmsx_Blackbox_GetDeviceStatus();
     cmsx_BlackboxDevice = blackboxConfig()->device;
 
     blackboxConfig_p_ratio = blackboxConfig()->p_ratio;
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Blackbox_onExit(const OSD_Entry *self)
+static const void *cmsx_Blackbox_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -194,7 +194,8 @@ static long cmsx_Blackbox_onExit(const OSD_Entry *self)
         blackboxValidateConfig();
     }
     blackboxConfigMutable()->p_ratio = blackboxConfig_p_ratio;
-    return 0;
+
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuBlackboxEntries[] =
diff --git a/src/main/cms/cms_menu_failsafe.c b/src/main/cms/cms_menu_failsafe.c
index 5c818005e..e5642802e 100644
--- a/src/main/cms/cms_menu_failsafe.c
+++ b/src/main/cms/cms_menu_failsafe.c
@@ -48,16 +48,17 @@ uint8_t failsafeConfig_failsafe_delay;
 uint8_t failsafeConfig_failsafe_off_delay;
 uint16_t failsafeConfig_failsafe_throttle;
 
-static long cmsx_Failsafe_onEnter(void)
+static const void *cmsx_Failsafe_onEnter(void)
 {
     failsafeConfig_failsafe_procedure = failsafeConfig()->failsafe_procedure;
     failsafeConfig_failsafe_delay = failsafeConfig()->failsafe_delay;
     failsafeConfig_failsafe_off_delay = failsafeConfig()->failsafe_off_delay;
     failsafeConfig_failsafe_throttle = failsafeConfig()->failsafe_throttle;
-    return 0;
+
+    return NULL;
 }
 
-static long cmsx_Failsafe_onExit(const OSD_Entry *self)
+static const void *cmsx_Failsafe_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -66,7 +67,7 @@ static long cmsx_Failsafe_onExit(const OSD_Entry *self)
     failsafeConfigMutable()->failsafe_off_delay = failsafeConfig_failsafe_off_delay;
     failsafeConfigMutable()->failsafe_throttle = failsafeConfig_failsafe_throttle;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuFailsafeEntries[] =
diff --git a/src/main/cms/cms_menu_firmware.c b/src/main/cms/cms_menu_firmware.c
index 3f6d0929c..0c0ff4935 100644
--- a/src/main/cms/cms_menu_firmware.c
+++ b/src/main/cms/cms_menu_firmware.c
@@ -65,7 +65,7 @@ static char accCalibrationStatus[CALIBRATION_STATUS_MAX_LENGTH];
 static char baroCalibrationStatus[CALIBRATION_STATUS_MAX_LENGTH];
 #endif
 
-static long cmsx_CalibrationOnDisplayUpdate(const OSD_Entry *selected)
+static const void *cmsx_CalibrationOnDisplayUpdate(const OSD_Entry *selected)
 {
     UNUSED(selected);
 
@@ -77,10 +77,10 @@ static long cmsx_CalibrationOnDisplayUpdate(const OSD_Entry *selected)
     tfp_sprintf(baroCalibrationStatus, sensors(SENSOR_BARO) ? baroIsCalibrationComplete() ? CALIBRATION_STATUS_OK : CALIBRATION_STATUS_WAIT: CALIBRATION_STATUS_OFF);
 #endif
 
-    return 0;
+    return NULL;
 }
 
-static long cmsCalibrateGyro(displayPort_t *pDisp, const void *self)
+static const void *cmsCalibrateGyro(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -89,11 +89,11 @@ static long cmsCalibrateGyro(displayPort_t *pDisp, const void *self)
         gyroStartCalibration(false);
     }
 
-    return 0;
+    return NULL;
 }
 
 #if defined(USE_ACC)
-static long cmsCalibrateAcc(displayPort_t *pDisp, const void *self)
+static const void *cmsCalibrateAcc(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -102,12 +102,12 @@ static long cmsCalibrateAcc(displayPort_t *pDisp, const void *self)
         accStartCalibration();
     }
 
-    return 0;
+    return NULL;
 }
 #endif
 
 #if defined(USE_BARO)
-static long cmsCalibrateBaro(displayPort_t *pDisp, const void *self)
+static const void *cmsCalibrateBaro(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -116,7 +116,7 @@ static long cmsCalibrateBaro(displayPort_t *pDisp, const void *self)
         baroStartCalibration();
     }
 
-    return 0;
+    return NULL;
 }
 #endif
 
@@ -149,7 +149,7 @@ static CMS_Menu cmsx_menuCalibration = {
 static char infoGitRev[GIT_SHORT_REVISION_LENGTH + 1];
 static char infoTargetName[] = __TARGET__;
 
-static long cmsx_FirmwareInit(void)
+static const void *cmsx_FirmwareInit(void)
 {
     unsigned i;
     for (i = 0 ; i < GIT_SHORT_REVISION_LENGTH ; i++) {
@@ -162,7 +162,7 @@ static long cmsx_FirmwareInit(void)
 
     infoGitRev[i] = 0x0; // Terminate string
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry menuFirmwareEntries[] = {
diff --git a/src/main/cms/cms_menu_gps_rescue.c b/src/main/cms/cms_menu_gps_rescue.c
index 54349319a..8e7642f0a 100644
--- a/src/main/cms/cms_menu_gps_rescue.c
+++ b/src/main/cms/cms_menu_gps_rescue.c
@@ -59,7 +59,7 @@ static uint8_t gpsRescueConfig_altitudeMode;
 static uint16_t gpsRescueConfig_ascendRate;
 static uint16_t gpsRescueConfig_descendRate;
 
-static long cms_menuGpsRescuePidOnEnter(void)
+static const void *cms_menuGpsRescuePidOnEnter(void)
 {
 
     gpsRescueConfig_throttleP = gpsRescueConfig()->throttleP;
@@ -72,10 +72,10 @@ static long cms_menuGpsRescuePidOnEnter(void)
     gpsRescueConfig_velI = gpsRescueConfig()->velI;
     gpsRescueConfig_velD = gpsRescueConfig()->velD;
 
-    return 0;
+    return NULL;
 }
 
-static long cms_menuGpsRescuePidOnExit(const OSD_Entry *self)
+static const void *cms_menuGpsRescuePidOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -89,7 +89,7 @@ static long cms_menuGpsRescuePidOnExit(const OSD_Entry *self)
     gpsRescueConfigMutable()->velI = gpsRescueConfig_velI;
     gpsRescueConfigMutable()->velD = gpsRescueConfig_velD;
 
-    return 0;
+    return NULL;
 }
 
 const OSD_Entry cms_menuGpsRescuePidEntries[] =
@@ -121,7 +121,7 @@ CMS_Menu cms_menuGpsRescuePid = {
     .entries = cms_menuGpsRescuePidEntries,
 };
 
-static long cmsx_menuGpsRescueOnEnter(void)
+static const void *cmsx_menuGpsRescueOnEnter(void)
 {
 
     gpsRescueConfig_angle = gpsRescueConfig()->angle;
@@ -140,10 +140,10 @@ static long cmsx_menuGpsRescueOnEnter(void)
     gpsRescueConfig_ascendRate = gpsRescueConfig()->ascendRate;
     gpsRescueConfig_descendRate = gpsRescueConfig()->descendRate;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuGpsRescueOnExit(const OSD_Entry *self)
+static const void *cmsx_menuGpsRescueOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -164,7 +164,7 @@ static long cmsx_menuGpsRescueOnExit(const OSD_Entry *self)
     gpsRescueConfigMutable()->ascendRate = gpsRescueConfig_ascendRate;
     gpsRescueConfigMutable()->descendRate = gpsRescueConfig_descendRate;
 
-    return 0;
+    return NULL;
 }
 
 const OSD_Entry cmsx_menuGpsRescueEntries[] =
diff --git a/src/main/cms/cms_menu_imu.c b/src/main/cms/cms_menu_imu.c
index 78a75e081..29c224b6f 100644
--- a/src/main/cms/cms_menu_imu.c
+++ b/src/main/cms/cms_menu_imu.c
@@ -112,7 +112,7 @@ static void setProfileIndexString(char *profileString, int profileIndex, char *p
     profileString[charIndex] = '\0';
 }
 
-static long cmsx_menuImu_onEnter(void)
+static const void *cmsx_menuImu_onEnter(void)
 {
     pidProfileIndex = getCurrentPidProfileIndex();
     tmpPidProfileIndex = pidProfileIndex + 1;
@@ -120,20 +120,20 @@ static long cmsx_menuImu_onEnter(void)
     rateProfileIndex = getCurrentControlRateProfileIndex();
     tmpRateProfileIndex = rateProfileIndex + 1;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuImu_onExit(const OSD_Entry *self)
+static const void *cmsx_menuImu_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
     changePidProfile(pidProfileIndex);
     changeControlRateProfile(rateProfileIndex);
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_profileIndexOnChange(displayPort_t *displayPort, const void *ptr)
+static const void *cmsx_profileIndexOnChange(displayPort_t *displayPort, const void *ptr)
 {
     UNUSED(displayPort);
     UNUSED(ptr);
@@ -141,10 +141,10 @@ static long cmsx_profileIndexOnChange(displayPort_t *displayPort, const void *pt
     pidProfileIndex = tmpPidProfileIndex - 1;
     changePidProfile(pidProfileIndex);
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_rateProfileIndexOnChange(displayPort_t *displayPort, const void *ptr)
+static const void *cmsx_rateProfileIndexOnChange(displayPort_t *displayPort, const void *ptr)
 {
     UNUSED(displayPort);
     UNUSED(ptr);
@@ -152,10 +152,10 @@ static long cmsx_rateProfileIndexOnChange(displayPort_t *displayPort, const void
     rateProfileIndex = tmpRateProfileIndex - 1;
     changeControlRateProfile(rateProfileIndex);
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_PidRead(void)
+static const void *cmsx_PidRead(void)
 {
 
     const pidProfile_t *pidProfile = pidProfiles(pidProfileIndex);
@@ -166,18 +166,18 @@ static long cmsx_PidRead(void)
         tempPidF[i] = pidProfile->pid[i].F;
     }
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_PidOnEnter(void)
+static const void *cmsx_PidOnEnter(void)
 {
     setProfileIndexString(pidProfileIndexString, pidProfileIndex, currentPidProfile->profileName);
     cmsx_PidRead();
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_PidWriteback(const OSD_Entry *self)
+static const void *cmsx_PidWriteback(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -190,7 +190,7 @@ static long cmsx_PidWriteback(const OSD_Entry *self)
     }
     pidInitConfig(currentPidProfile);
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuPidEntries[] =
@@ -231,28 +231,28 @@ static CMS_Menu cmsx_menuPid = {
 // Rate & Expo
 //
 
-static long cmsx_RateProfileRead(void)
+static const void *cmsx_RateProfileRead(void)
 {
     memcpy(&rateProfile, controlRateProfiles(rateProfileIndex), sizeof(controlRateConfig_t));
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_RateProfileWriteback(const OSD_Entry *self)
+static const void *cmsx_RateProfileWriteback(const OSD_Entry *self)
 {
     UNUSED(self);
 
     memcpy(controlRateProfilesMutable(rateProfileIndex), &rateProfile, sizeof(controlRateConfig_t));
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_RateProfileOnEnter(void)
+static const void *cmsx_RateProfileOnEnter(void)
 {
     setProfileIndexString(rateProfileIndexString, rateProfileIndex, controlRateProfilesMutable(rateProfileIndex)->profileName);
     cmsx_RateProfileRead();
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuRateProfileEntries[] =
@@ -301,7 +301,7 @@ static uint8_t cmsx_launchControlThrottlePercent;
 static uint8_t cmsx_launchControlAngleLimit;
 static uint8_t cmsx_launchControlGain;
 
-static long cmsx_launchControlOnEnter(void)
+static const void *cmsx_launchControlOnEnter(void)
 {
     const pidProfile_t *pidProfile = pidProfiles(pidProfileIndex);
 
@@ -311,10 +311,10 @@ static long cmsx_launchControlOnEnter(void)
     cmsx_launchControlAngleLimit  = pidProfile->launchControlAngleLimit;
     cmsx_launchControlGain  = pidProfile->launchControlGain;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_launchControlOnExit(const OSD_Entry *self)
+static const void *cmsx_launchControlOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -326,7 +326,7 @@ static long cmsx_launchControlOnExit(const OSD_Entry *self)
     pidProfile->launchControlAngleLimit = cmsx_launchControlAngleLimit;
     pidProfile->launchControlGain = cmsx_launchControlGain;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuLaunchControlEntries[] = {
@@ -376,7 +376,7 @@ static uint8_t cmsx_iterm_relax_type;
 static uint8_t cmsx_iterm_relax_cutoff;
 #endif
 
-static long cmsx_profileOtherOnEnter(void)
+static const void *cmsx_profileOtherOnEnter(void)
 {
     setProfileIndexString(pidProfileIndexString, pidProfileIndex, currentPidProfile->profileName);
 
@@ -410,10 +410,10 @@ static long cmsx_profileOtherOnEnter(void)
     cmsx_iterm_relax_cutoff = pidProfile->iterm_relax_cutoff;
 #endif
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_profileOtherOnExit(const OSD_Entry *self)
+static const void *cmsx_profileOtherOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -448,7 +448,7 @@ static long cmsx_profileOtherOnExit(const OSD_Entry *self)
 #endif
 
     initEscEndpoints();
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuProfileOtherEntries[] = {
@@ -508,7 +508,7 @@ static uint16_t gyroConfig_gyro_soft_notch_hz_2;
 static uint16_t gyroConfig_gyro_soft_notch_cutoff_2;
 static uint8_t  gyroConfig_gyro_to_use;
 
-static long cmsx_menuGyro_onEnter(void)
+static const void *cmsx_menuGyro_onEnter(void)
 {
     gyroConfig_gyro_lowpass_hz =  gyroConfig()->gyro_lowpass_hz;
     gyroConfig_gyro_lowpass2_hz =  gyroConfig()->gyro_lowpass2_hz;
@@ -518,10 +518,10 @@ static long cmsx_menuGyro_onEnter(void)
     gyroConfig_gyro_soft_notch_cutoff_2 = gyroConfig()->gyro_soft_notch_cutoff_2;
     gyroConfig_gyro_to_use = gyroConfig()->gyro_to_use;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuGyro_onExit(const OSD_Entry *self)
+static const void *cmsx_menuGyro_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -533,7 +533,7 @@ static long cmsx_menuGyro_onExit(const OSD_Entry *self)
     gyroConfigMutable()->gyro_soft_notch_cutoff_2 = gyroConfig_gyro_soft_notch_cutoff_2;
     gyroConfigMutable()->gyro_to_use = gyroConfig_gyro_to_use;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuFilterGlobalEntries[] =
@@ -582,7 +582,7 @@ static uint16_t dynFiltDtermMin;
 static uint16_t dynFiltDtermMax;
 #endif
 
-static long cmsx_menuDynFilt_onEnter(void)
+static const void *cmsx_menuDynFilt_onEnter(void)
 {
 #ifdef USE_GYRO_DATA_ANALYSE
     dynFiltNotchRange   = gyroConfig()->dyn_notch_range;
@@ -598,10 +598,10 @@ static long cmsx_menuDynFilt_onEnter(void)
     dynFiltDtermMax = pidProfile->dyn_lpf_dterm_max_hz;
 #endif
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuDynFilt_onExit(const OSD_Entry *self)
+static const void *cmsx_menuDynFilt_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -619,7 +619,7 @@ static long cmsx_menuDynFilt_onExit(const OSD_Entry *self)
     pidProfile->dyn_lpf_dterm_max_hz         = dynFiltDtermMax;
 #endif
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuDynFiltEntries[] =
@@ -663,7 +663,7 @@ static uint16_t cmsx_dterm_notch_hz;
 static uint16_t cmsx_dterm_notch_cutoff;
 static uint16_t cmsx_yaw_lowpass_hz;
 
-static long cmsx_FilterPerProfileRead(void)
+static const void *cmsx_FilterPerProfileRead(void)
 {
     const pidProfile_t *pidProfile = pidProfiles(pidProfileIndex);
 
@@ -673,10 +673,10 @@ static long cmsx_FilterPerProfileRead(void)
     cmsx_dterm_notch_cutoff = pidProfile->dterm_notch_cutoff;
     cmsx_yaw_lowpass_hz     = pidProfile->yaw_lowpass_hz;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_FilterPerProfileWriteback(const OSD_Entry *self)
+static const void *cmsx_FilterPerProfileWriteback(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -688,7 +688,7 @@ static long cmsx_FilterPerProfileWriteback(const OSD_Entry *self)
     pidProfile->dterm_notch_cutoff = cmsx_dterm_notch_cutoff;
     pidProfile->yaw_lowpass_hz     = cmsx_yaw_lowpass_hz;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuFilterPerProfileEntries[] =
@@ -731,15 +731,15 @@ static const char * const cmsx_ProfileNames[] = {
 static OSD_TAB_t cmsx_PidProfileTable = { &cmsx_dstPidProfile, 3, cmsx_ProfileNames };
 static OSD_TAB_t cmsx_ControlRateProfileTable = { &cmsx_dstControlRateProfile, 3, cmsx_ProfileNames };
 
-static long cmsx_menuCopyProfile_onEnter(void)
+static const void *cmsx_menuCopyProfile_onEnter(void)
 {
     cmsx_dstPidProfile = 0;
     cmsx_dstControlRateProfile = 0;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_CopyPidProfile(displayPort_t *pDisplay, const void *ptr)
+static const void *cmsx_CopyPidProfile(displayPort_t *pDisplay, const void *ptr)
 {
     UNUSED(pDisplay);
     UNUSED(ptr);
@@ -748,10 +748,10 @@ static long cmsx_CopyPidProfile(displayPort_t *pDisplay, const void *ptr)
         pidCopyProfile(cmsx_dstPidProfile - 1, getCurrentPidProfileIndex());
     }
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_CopyControlRateProfile(displayPort_t *pDisplay, const void *ptr)
+static const void *cmsx_CopyControlRateProfile(displayPort_t *pDisplay, const void *ptr)
 {
     UNUSED(pDisplay);
     UNUSED(ptr);
@@ -760,7 +760,7 @@ static long cmsx_CopyControlRateProfile(displayPort_t *pDisplay, const void *ptr
         copyControlRateProfile(cmsx_dstControlRateProfile - 1, getCurrentControlRateProfileIndex());
     }
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuCopyProfileEntries[] =
diff --git a/src/main/cms/cms_menu_ledstrip.c b/src/main/cms/cms_menu_ledstrip.c
index 67b830f79..99d505ebf 100644
--- a/src/main/cms/cms_menu_ledstrip.c
+++ b/src/main/cms/cms_menu_ledstrip.c
@@ -65,7 +65,7 @@ const char * const ledProfileNames[LED_PROFILE_COUNT] = {
 #endif
 };
 
-static long cmsx_Ledstrip_OnEnter(void)
+static const void *cmsx_Ledstrip_OnEnter(void)
 {
     cmsx_FeatureLedstrip = featureIsEnabled(FEATURE_LED_STRIP) ? 1 : 0;
     cmsx_ledProfile = getLedProfile();
@@ -77,10 +77,10 @@ static long cmsx_Ledstrip_OnEnter(void)
     cmsx_ledVisualBeeper = ledStripConfig()->ledstrip_visual_beeper;
     cmsx_ledVisualBeeperColor = ledStripConfig()->ledstrip_visual_beeper_color;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Ledstrip_OnExit(const OSD_Entry *self)
+static const void *cmsx_Ledstrip_OnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -101,7 +101,7 @@ static long cmsx_Ledstrip_OnExit(const OSD_Entry *self)
     ledStripConfigMutable()->ledstrip_visual_beeper = cmsx_ledVisualBeeper;
     ledStripConfigMutable()->ledstrip_visual_beeper_color = cmsx_ledVisualBeeperColor;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuLedstripEntries[] =
diff --git a/src/main/cms/cms_menu_main.c b/src/main/cms/cms_menu_main.c
index 9bd6d147e..0a6eb5bc5 100644
--- a/src/main/cms/cms_menu_main.c
+++ b/src/main/cms/cms_menu_main.c
@@ -88,7 +88,7 @@ static CMS_Menu cmsx_menuFeatures = {
     .entries = menuFeaturesEntries,
 };
 
-static long cmsx_SaveExitMenu(displayPort_t *pDisplay, const void *ptr)
+static const void *cmsx_SaveExitMenu(displayPort_t *pDisplay, const void *ptr)
 {
     UNUSED(ptr);
 
@@ -97,7 +97,7 @@ static long cmsx_SaveExitMenu(displayPort_t *pDisplay, const void *ptr)
     } else {
         cmsMenuChange(pDisplay, &cmsx_menuSaveExit);
     }
-    return 0;
+    return NULL;
 }
 
 // Main
diff --git a/src/main/cms/cms_menu_misc.c b/src/main/cms/cms_menu_misc.c
index d5a3d1ed8..c7f5d23e2 100644
--- a/src/main/cms/cms_menu_misc.c
+++ b/src/main/cms/cms_menu_misc.c
@@ -60,12 +60,12 @@
 // Misc
 //
 
-static long cmsx_menuRcConfirmBack(const OSD_Entry *self)
+static const void *cmsx_menuRcConfirmBack(const OSD_Entry *self)
 {
     if (self && self->type == OME_Back)
-        return 0;
+        return NULL;
     else
-        return -1;
+        return MENU_CHAIN_BACK;
 }
 
 //
@@ -105,17 +105,17 @@ static uint8_t motorConfig_digitalIdleOffsetValue;
 static uint8_t rxConfig_fpvCamAngleDegrees;
 static debugType_e systemConfig_debug_mode;
 
-static long cmsx_menuMiscOnEnter(void)
+static const void *cmsx_menuMiscOnEnter(void)
 {
     motorConfig_minthrottle = motorConfig()->minthrottle;
     motorConfig_digitalIdleOffsetValue = motorConfig()->digitalIdleOffsetValue / 10;
     rxConfig_fpvCamAngleDegrees = rxConfig()->fpvCamAngleDegrees;
     systemConfig_debug_mode = systemConfig()->debug_mode;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuMiscOnExit(const OSD_Entry *self)
+static const void *cmsx_menuMiscOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -124,7 +124,7 @@ static long cmsx_menuMiscOnExit(const OSD_Entry *self)
     rxConfigMutable()->fpvCamAngleDegrees = rxConfig_fpvCamAngleDegrees;
     systemConfigMutable()->debug_mode = systemConfig_debug_mode;
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry menuMiscEntries[]=
diff --git a/src/main/cms/cms_menu_osd.c b/src/main/cms/cms_menu_osd.c
index f088c0e8d..030d1c785 100644
--- a/src/main/cms/cms_menu_osd.c
+++ b/src/main/cms/cms_menu_osd.c
@@ -48,19 +48,19 @@
 #ifdef USE_EXTENDED_CMS_MENUS
 static uint16_t osdConfig_item_pos[OSD_ITEM_COUNT];
 
-static long menuOsdActiveElemsOnEnter(void)
+static const void *menuOsdActiveElemsOnEnter(void)
 {
     memcpy(&osdConfig_item_pos[0], &osdConfig()->item_pos[0], sizeof(uint16_t) * OSD_ITEM_COUNT);
-    return 0;
+    return NULL;
 }
 
-static long menuOsdActiveElemsOnExit(const OSD_Entry *self)
+static const void *menuOsdActiveElemsOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
     memcpy(&osdConfigMutable()->item_pos[0], &osdConfig_item_pos[0], sizeof(uint16_t) * OSD_ITEM_COUNT);
     osdAnalyzeActiveElements();
-    return 0;
+    return NULL;
 }
 
 const OSD_Entry menuOsdActiveElemsEntries[] =
@@ -171,7 +171,7 @@ static uint16_t osdConfig_distance_alarm;
 static uint8_t batteryConfig_vbatDurationForWarning;
 static uint8_t batteryConfig_vbatDurationForCritical;
 
-static long menuAlarmsOnEnter(void)
+static const void *menuAlarmsOnEnter(void)
 {
     osdConfig_rssi_alarm = osdConfig()->rssi_alarm;
     osdConfig_link_quality_alarm = osdConfig()->link_quality_alarm;
@@ -182,10 +182,10 @@ static long menuAlarmsOnEnter(void)
     batteryConfig_vbatDurationForWarning = batteryConfig()->vbatDurationForWarning;
     batteryConfig_vbatDurationForCritical = batteryConfig()->vbatDurationForCritical;
 
-    return 0;
+    return NULL;
 }
 
-static long menuAlarmsOnExit(const OSD_Entry *self)
+static const void *menuAlarmsOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -198,7 +198,7 @@ static long menuAlarmsOnExit(const OSD_Entry *self)
     batteryConfigMutable()->vbatDurationForWarning = batteryConfig_vbatDurationForWarning;
     batteryConfigMutable()->vbatDurationForCritical = batteryConfig_vbatDurationForCritical;
 
-    return 0;
+    return NULL;
 }
 
 const OSD_Entry menuAlarmsEntries[] =
@@ -231,7 +231,7 @@ osd_timer_source_e timerSource[OSD_TIMER_COUNT];
 osd_timer_precision_e timerPrecision[OSD_TIMER_COUNT];
 uint8_t timerAlarm[OSD_TIMER_COUNT];
 
-static long menuTimersOnEnter(void)
+static const void *menuTimersOnEnter(void)
 {
     for (int i = 0; i < OSD_TIMER_COUNT; i++) {
         const uint16_t timer = osdConfig()->timers[i];
@@ -240,10 +240,10 @@ static long menuTimersOnEnter(void)
         timerAlarm[i] = OSD_TIMER_ALARM(timer);
     }
 
-    return 0;
+    return NULL;
 }
 
-static long menuTimersOnExit(const OSD_Entry *self)
+static const void *menuTimersOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -251,7 +251,7 @@ static long menuTimersOnExit(const OSD_Entry *self)
         osdConfigMutable()->timers[i] = OSD_TIMER(timerSource[i], timerPrecision[i], timerAlarm[i]);
     }
 
-    return 0;
+    return NULL;
 }
 
 static const char * osdTimerPrecisionNames[] = {"SCND", "HDTH"};
@@ -291,7 +291,7 @@ static uint8_t displayPortProfileMax7456_whiteBrightness;
 static uint8_t osdConfig_osdProfileIndex;
 #endif
 
-static long cmsx_menuOsdOnEnter(void)
+static const void *cmsx_menuOsdOnEnter(void)
 {
 #ifdef USE_OSD_PROFILES
     osdConfig_osdProfileIndex = osdConfig()->osdProfileIndex;
@@ -303,10 +303,10 @@ static long cmsx_menuOsdOnEnter(void)
     displayPortProfileMax7456_whiteBrightness = displayPortProfileMax7456()->whiteBrightness;
 #endif
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_menuOsdOnExit(const OSD_Entry *self)
+static const void *cmsx_menuOsdOnExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -320,7 +320,7 @@ static long cmsx_menuOsdOnExit(const OSD_Entry *self)
     displayPortProfileMax7456Mutable()->whiteBrightness = displayPortProfileMax7456_whiteBrightness;
 #endif
 
-    return 0;
+    return NULL;
 }
 
 const OSD_Entry cmsx_menuOsdEntries[] =
diff --git a/src/main/cms/cms_menu_power.c b/src/main/cms/cms_menu_power.c
index 55c3e66c3..814b94b23 100644
--- a/src/main/cms/cms_menu_power.c
+++ b/src/main/cms/cms_menu_power.c
@@ -54,7 +54,7 @@ int16_t currentSensorVirtualConfig_scale;
 int16_t currentSensorVirtualConfig_offset;
 #endif
 
-static long cmsx_Power_onEnter(void)
+static const void *cmsx_Power_onEnter(void)
 {
     batteryConfig_voltageMeterSource = batteryConfig()->voltageMeterSource;
     batteryConfig_currentMeterSource = batteryConfig()->currentMeterSource;
@@ -71,10 +71,10 @@ static long cmsx_Power_onEnter(void)
     currentSensorVirtualConfig_offset = currentSensorVirtualConfig()->offset;
 #endif
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Power_onExit(const OSD_Entry *self)
+static const void *cmsx_Power_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
@@ -93,7 +93,7 @@ static long cmsx_Power_onExit(const OSD_Entry *self)
     currentSensorVirtualConfigMutable()->offset = currentSensorVirtualConfig_offset;
 #endif
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuPowerEntries[] =
diff --git a/src/main/cms/cms_menu_vtx_common.c b/src/main/cms/cms_menu_vtx_common.c
index 3adf458ed..b6238141b 100644
--- a/src/main/cms/cms_menu_vtx_common.c
+++ b/src/main/cms/cms_menu_vtx_common.c
@@ -43,7 +43,7 @@
 static char statusLine1[MAX_STATUS_LINE_LENGTH] = "";
 static char statusLine2[MAX_STATUS_LINE_LENGTH] = "";
 
-static long setStatusMessage(void)
+static const void *setStatusMessage(void)
 {
     vtxDevice_t *device = vtxCommonDevice();
 
@@ -61,7 +61,7 @@ static long setStatusMessage(void)
             tfp_sprintf(&statusLine1[0], "UNKNOWN VTX TYPE");
         }
     }
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry vtxErrorMenuEntries[] =
@@ -87,7 +87,7 @@ static CMS_Menu cmsx_menuVtxError = {
 // Redirect to the proper menu based on the vtx device type
 // If device isn't valid or not a supported type then don't
 // redirect and instead display a local informational menu.
-long cmsSelectVtx(displayPort_t *pDisplay, const void *ptr)
+const void *cmsSelectVtx(displayPort_t *pDisplay, const void *ptr)
 {
     UNUSED(ptr);
 
@@ -126,6 +126,6 @@ long cmsSelectVtx(displayPort_t *pDisplay, const void *ptr)
         cmsMenuChange(pDisplay, &cmsx_menuVtxError);
     }
 
-    return 0;
+    return NULL;
 }
 #endif
diff --git a/src/main/cms/cms_menu_vtx_common.h b/src/main/cms/cms_menu_vtx_common.h
index 878dbbd9b..0cb14a1dd 100644
--- a/src/main/cms/cms_menu_vtx_common.h
+++ b/src/main/cms/cms_menu_vtx_common.h
@@ -23,4 +23,4 @@
 #include "cms/cms.h"
 #include "cms/cms_types.h"
 
-long cmsSelectVtx(displayPort_t *pDisplay, const void *ptr);
+const void *cmsSelectVtx(displayPort_t *pDisplay, const void *ptr);
diff --git a/src/main/cms/cms_menu_vtx_rtc6705.c b/src/main/cms/cms_menu_vtx_rtc6705.c
index 685e6d0ad..461d853c2 100644
--- a/src/main/cms/cms_menu_vtx_rtc6705.c
+++ b/src/main/cms/cms_menu_vtx_rtc6705.c
@@ -78,7 +78,7 @@ static void cmsx_Vtx_ConfigWriteback(void)
     saveConfigAndNotify();
 }
 
-static long cmsx_Vtx_onEnter(void)
+static const void *cmsx_Vtx_onEnter(void)
 {
     cmsx_Vtx_ConfigRead();
 
@@ -94,57 +94,57 @@ static long cmsx_Vtx_onEnter(void)
     entryVtxPower.max = vtxTablePowerLevels;
     entryVtxPower.names = vtxTablePowerLabels;
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Vtx_onExit(const OSD_Entry *self)
+static const void *cmsx_Vtx_onExit(const OSD_Entry *self)
 {
     UNUSED(self);
 
     vtxCommonSetPitMode(vtxCommonDevice(), cmsx_vtxPit);
     cmsx_Vtx_ConfigWriteback();
 
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Vtx_onBandChange(displayPort_t *pDisp, const void *self)
+static const void *cmsx_Vtx_onBandChange(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
     if (cmsx_vtxBand == 0) {
         cmsx_vtxBand = 1;
     }
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Vtx_onChanChange(displayPort_t *pDisp, const void *self)
+static const void *cmsx_Vtx_onChanChange(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
     if (cmsx_vtxChannel == 0) {
         cmsx_vtxChannel = 1;
     }
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Vtx_onPowerChange(displayPort_t *pDisp, const void *self)
+static const void *cmsx_Vtx_onPowerChange(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
     if (cmsx_vtxPower == 0) {
         cmsx_vtxPower = 1;
     }
-    return 0;
+    return NULL;
 }
 
-static long cmsx_Vtx_onPitChange(displayPort_t *pDisp, const void *self)
+static const void *cmsx_Vtx_onPitChange(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
     if (cmsx_vtxPit == 0) {
         cmsx_vtxPit = 1;
     }
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry cmsx_menuVtxEntries[] = {
diff --git a/src/main/cms/cms_menu_vtx_smartaudio.c b/src/main/cms/cms_menu_vtx_smartaudio.c
index ec9c10cf8..2d672840e 100644
--- a/src/main/cms/cms_menu_vtx_smartaudio.c
+++ b/src/main/cms/cms_menu_vtx_smartaudio.c
@@ -121,12 +121,12 @@ char saCmsStatusString[31] = "- -- ---- ---";
 //                            m bc ffff ppp
 //                            0123456789012
 
-static long saCmsConfigOpmodelByGvar(displayPort_t *, const void *self);
-static long saCmsConfigPitFModeByGvar(displayPort_t *, const void *self);
-static long saCmsConfigBandByGvar(displayPort_t *, const void *self);
-static long saCmsConfigChanByGvar(displayPort_t *, const void *self);
-static long saCmsConfigPowerByGvar(displayPort_t *, const void *self);
-static long saCmsConfigPitByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigOpmodelByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigPitFModeByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigBandByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigChanByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigPowerByGvar(displayPort_t *, const void *self);
+static const void *saCmsConfigPitByGvar(displayPort_t *, const void *self);
 
 void saUpdateStatusString(void)
 {
@@ -204,7 +204,7 @@ void saCmsResetOpmodel()
     saCmsOpmodel = SACMS_OPMODEL_UNDEF;
 }
 
-static long saCmsConfigBandByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigBandByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -212,13 +212,13 @@ static long saCmsConfigBandByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 0) {
         // Bounce back; not online yet
         saCmsBand = 0;
-        return 0;
+        return NULL;
     }
 
     if (saCmsBand == 0) {
         // Bouce back, no going back to undef state
         saCmsBand = 1;
-        return 0;
+        return NULL;
     }
 
     if ((saCmsOpmodel == SACMS_OPMODEL_FREE) && !saDeferred) {
@@ -227,10 +227,10 @@ static long saCmsConfigBandByGvar(displayPort_t *pDisp, const void *self)
 
     saCmsFreqRef = vtxCommonLookupFrequency(vtxCommonDevice(), saCmsBand, saCmsChan);
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigChanByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigChanByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -238,13 +238,13 @@ static long saCmsConfigChanByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 0) {
         // Bounce back; not online yet
         saCmsChan = 0;
-        return 0;
+        return NULL;
     }
 
     if (saCmsChan == 0) {
         // Bounce back; no going back to undef state
         saCmsChan = 1;
-        return 0;
+        return NULL;
     }
 
     if ((saCmsOpmodel == SACMS_OPMODEL_FREE) && !saDeferred) {
@@ -253,10 +253,10 @@ static long saCmsConfigChanByGvar(displayPort_t *pDisp, const void *self)
 
     saCmsFreqRef = vtxCommonLookupFrequency(vtxCommonDevice(), saCmsBand, saCmsChan);
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigPitByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigPitByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -266,21 +266,21 @@ static long saCmsConfigPitByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 0) {
         // Bounce back; not online yet
         saCmsPit = 0;
-        return 0;
+        return NULL;
     }
 
     if (saCmsPit == 0) {//trying to go back to undef state; bounce back
         saCmsPit = 1;
-        return 0;
+        return NULL;
     }
     if (saDevice.power != saCmsPower) {//we can't change both power and pit mode at once
         saCmsPower = saDevice.power;
     }
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigPowerByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigPowerByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -288,13 +288,13 @@ static long saCmsConfigPowerByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 0) {
         // Bounce back; not online yet
         saCmsPower = 0;
-        return 0;
+        return NULL;
     }
 
     if (saCmsPower == 0) {
         // Bouce back; no going back to undef state
         saCmsPower = 1;
-        return 0;
+        return NULL;
     }
 
     if (saCmsPit > 0 && saCmsPit != 1 ) {
@@ -306,10 +306,10 @@ static long saCmsConfigPowerByGvar(displayPort_t *pDisp, const void *self)
     }
     dprintf(("saCmsConfigPowerByGvar: power index is now %d\r\n", saCmsPower));
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigPitFModeByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigPitFModeByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -317,13 +317,13 @@ static long saCmsConfigPitFModeByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 1) {
         // V1 device doesn't support PIT mode; bounce back.
         saCmsPitFMode = 0;
-        return 0;
+        return NULL;
     }
     if (saDevice.version >= 3) {
         // V2.1 device only supports PIR mode. and setting any flag immediately enables pit mode.
         //therefore: bounce back.
         saCmsPitFMode = 1;
-        return 0;
+        return NULL;
     }
 
     dprintf(("saCmsConfigPitFmodeByGbar: saCmsPitFMode %d\r\n", saCmsPitFMode));
@@ -331,7 +331,7 @@ static long saCmsConfigPitFModeByGvar(displayPort_t *pDisp, const void *self)
     if (saCmsPitFMode == 0) {
         // Bounce back
         saCmsPitFMode = 1;
-        return 0;
+        return NULL;
     }
 
     if (saCmsPitFMode == 1) {
@@ -340,12 +340,12 @@ static long saCmsConfigPitFModeByGvar(displayPort_t *pDisp, const void *self)
         saSetMode(SA_MODE_SET_OUT_RANGE_PITMODE);
     }
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigFreqModeByGvar(displayPort_t *pDisp, const void *self); // Forward
+static const void *saCmsConfigFreqModeByGvar(displayPort_t *pDisp, const void *self); // Forward
 
-static long saCmsConfigOpmodelByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigOpmodelByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -353,7 +353,7 @@ static long saCmsConfigOpmodelByGvar(displayPort_t *pDisp, const void *self)
     if (saDevice.version == 1) {
         if (saCmsOpmodel != SACMS_OPMODEL_FREE)
             saCmsOpmodel = SACMS_OPMODEL_FREE;
-        return 0;
+        return NULL;
     }
 
     uint8_t opmodel = saCmsOpmodel;
@@ -382,7 +382,7 @@ static long saCmsConfigOpmodelByGvar(displayPort_t *pDisp, const void *self)
         saCmsOpmodel = SACMS_OPMODEL_UNDEF + 1;
     }
 
-    return 0;
+    return NULL;
 }
 
 #ifdef USE_EXTENDED_CMS_MENUS
@@ -468,9 +468,9 @@ static const char * const saCmsPitNames[] = {
 static OSD_TAB_t saCmsEntPitFMode = { &saCmsPitFMode, 1, saCmsPitFModeNames };
 static OSD_TAB_t saCmsEntPit = {&saCmsPit, 2, saCmsPitNames};
 
-static long sacms_SetupTopMenu(void); // Forward
+static const void *sacms_SetupTopMenu(void); // Forward
 
-static long saCmsConfigFreqModeByGvar(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigFreqModeByGvar(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -486,10 +486,10 @@ static long saCmsConfigFreqModeByGvar(displayPort_t *pDisp, const void *self)
 
     sacms_SetupTopMenu();
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsCommence(displayPort_t *pDisp, const void *self)
+static const void *saCmsCommence(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -540,28 +540,31 @@ static long saCmsCommence(displayPort_t *pDisp, const void *self)
     return MENU_CHAIN_BACK;
 }
 
-static long saCmsSetPORFreqOnEnter(void)
+static const void *saCmsSetPORFreqOnEnter(void)
 {
     if (saDevice.version == 1)
         return MENU_CHAIN_BACK;
 
     saCmsORFreqNew = saCmsORFreq;
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsSetPORFreq(displayPort_t *pDisp, const void *self)
+static const void *saCmsSetPORFreq(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
 
     saSetPitFreq(saCmsORFreqNew);
 
-    return 0;
+    return NULL;
 }
 
-static char *saCmsORFreqGetString(void)
+static const char *saCmsORFreqGetString(displayPort_t *pDisp, const void *self)
 {
+    UNUSED(pDisp);
+    UNUSED(self);
+
     static char pbuf[5];
 
     tfp_sprintf(pbuf, "%4d", saCmsORFreq);
@@ -569,8 +572,11 @@ static char *saCmsORFreqGetString(void)
     return pbuf;
 }
 
-static char *saCmsUserFreqGetString(void)
+static const char *saCmsUserFreqGetString(displayPort_t *pDisp, const void *self)
 {
+    UNUSED(pDisp);
+    UNUSED(self);
+
     static char pbuf[5];
 
     tfp_sprintf(pbuf, "%4d", saCmsUserFreq);
@@ -578,14 +584,14 @@ static char *saCmsUserFreqGetString(void)
     return pbuf;
 }
 
-static long saCmsSetUserFreqOnEnter(void)
+static const void *saCmsSetUserFreqOnEnter(void)
 {
     saCmsUserFreqNew = saCmsUserFreq;
 
-    return 0;
+    return NULL;
 }
 
-static long saCmsConfigUserFreq(displayPort_t *pDisp, const void *self)
+static const void *saCmsConfigUserFreq(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -735,7 +741,7 @@ static const OSD_Entry saCmsMenuOfflineEntries[] =
 
 CMS_Menu cmsx_menuVtxSmartAudio; // Forward
 
-static long sacms_SetupTopMenu(void)
+static const void *sacms_SetupTopMenu(void)
 {
     if (saCmsDeviceStatus) {
         if (saCmsFselModeNew == 0)
@@ -748,7 +754,7 @@ static long sacms_SetupTopMenu(void)
 
     saCmsInitNames();
 
-    return 0;
+    return NULL;
 }
 
 CMS_Menu cmsx_menuVtxSmartAudio = {
diff --git a/src/main/cms/cms_menu_vtx_tramp.c b/src/main/cms/cms_menu_vtx_tramp.c
index 872621d03..9f615bf57 100644
--- a/src/main/cms/cms_menu_vtx_tramp.c
+++ b/src/main/cms/cms_menu_vtx_tramp.c
@@ -100,7 +100,7 @@ static void trampCmsUpdateFreqRef(void)
     }
 }
 
-static long trampCmsConfigBand(displayPort_t *pDisp, const void *self)
+static const void *trampCmsConfigBand(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -111,10 +111,10 @@ static long trampCmsConfigBand(displayPort_t *pDisp, const void *self)
     else
         trampCmsUpdateFreqRef();
 
-    return 0;
+    return NULL;
 }
 
-static long trampCmsConfigChan(displayPort_t *pDisp, const void *self)
+static const void *trampCmsConfigChan(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -125,10 +125,10 @@ static long trampCmsConfigChan(displayPort_t *pDisp, const void *self)
     else
         trampCmsUpdateFreqRef();
 
-    return 0;
+    return NULL;
 }
 
-static long trampCmsConfigPower(displayPort_t *pDisp, const void *self)
+static const void *trampCmsConfigPower(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -137,7 +137,7 @@ static long trampCmsConfigPower(displayPort_t *pDisp, const void *self)
         // Bounce back
         trampCmsPower = 1;
 
-    return 0;
+    return NULL;
 }
 
 static OSD_INT16_t trampCmsEntTemp = { &trampTemperature, -100, 300, 0 };
@@ -148,7 +148,7 @@ static const char * const trampCmsPitModeNames[] = {
 
 static OSD_TAB_t trampCmsEntPitMode = { &trampCmsPitMode, 2, trampCmsPitModeNames };
 
-static long trampCmsSetPitMode(displayPort_t *pDisp, const void *self)
+static const void *trampCmsSetPitMode(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -160,10 +160,10 @@ static long trampCmsSetPitMode(displayPort_t *pDisp, const void *self)
         trampSetPitMode(trampCmsPitMode - 1);
     }
 
-    return 0;
+    return NULL;
 }
 
-static long trampCmsCommence(displayPort_t *pDisp, const void *self)
+static const void *trampCmsCommence(displayPort_t *pDisp, const void *self)
 {
     UNUSED(pDisp);
     UNUSED(self);
@@ -220,13 +220,13 @@ static bool trampCmsInitSettings(void)
     return true;
 }
 
-static long trampCmsOnEnter(void)
+static const void *trampCmsOnEnter(void)
 {
     if (!trampCmsInitSettings()) {
         return MENU_CHAIN_BACK;
     }
 
-    return 0;
+    return NULL;
 }
 
 static const OSD_Entry trampCmsMenuCommenceEntries[] = {
diff --git a/src/main/cms/cms_types.h b/src/main/cms/cms_types.h
index 7d3f8e794..3bfe3bcd9 100644
--- a/src/main/cms/cms_types.h
+++ b/src/main/cms/cms_types.h
@@ -54,13 +54,13 @@ typedef enum
     OME_MAX = OME_MENU
 } OSD_MenuElement;
 
-typedef long (*CMSEntryFuncPtr)(displayPort_t *displayPort, const void *ptr);
+typedef const void *(*CMSEntryFuncPtr)(displayPort_t *displayPort, const void *ptr);
 
 typedef struct
 {
     const char * const text;
     const OSD_MenuElement type;
-    const CMSEntryFuncPtr func;
+    CMSEntryFuncPtr func;
     void *data;
     const uint8_t flags;
 } __attribute__((packed)) OSD_Entry;
@@ -82,10 +82,11 @@ typedef struct
 
 #define IS_DYNAMIC(p) ((p)->flags & DYNAMIC)
 
-typedef long (*CMSMenuFuncPtr)(void);
+typedef const void *(*CMSMenuFuncPtr)(void);
 
 // Special return value(s) for function chaining by CMSMenuFuncPtr
-#define MENU_CHAIN_BACK  (-1) // Causes automatic cmsMenuBack
+extern int menuChainBack;
+#define MENU_CHAIN_BACK  (&menuChainBack) // Causes automatic cmsMenuBack
 
 /*
 onExit function is called with self:
@@ -94,11 +95,11 @@ onExit function is called with self:
 (2) NULL if called from menu exit (forced exit at top level).
 */
 
-typedef long (*CMSMenuOnExitPtr)(const OSD_Entry *self);
+typedef const void *(*CMSMenuOnExitPtr)(const OSD_Entry *self);
 
 typedef const void * (*CMSMenuCheckRedirectPtr)(void);
 
-typedef long (*CMSMenuOnDisplayUpdatePtr)(const OSD_Entry *selected);
+typedef const void *(*CMSMenuOnDisplayUpdatePtr)(const OSD_Entry *selected);
 
 typedef struct
 {
@@ -165,7 +166,3 @@ typedef struct
 {
     char *val;
 } OSD_String_t;
-
-// This is a function used in the func member if the type is OME_Submenu.
-
-typedef char * (*CMSMenuOptFuncPtr)(void);
diff --git a/src/main/target/common_defaults_post.h b/src/main/target/common_defaults_post.h
index cb642120b..965ade227 100644
--- a/src/main/target/common_defaults_post.h
+++ b/src/main/target/common_defaults_post.h
@@ -680,5 +680,5 @@
 
 // XXX Tentative; may be removed
 #if defined(USE_MSP_DISPLAYPORT) && defined(USE_OSD_OVER_MSP_DISPLAYPORT)
-#define USE_DISPLAYPORT_MSP_VENDOR_SPECIFIC
+//#define USE_DISPLAYPORT_MSP_VENDOR_SPECIFIC
 #endif
diff --git a/src/test/unit/cms_unittest.cc b/src/test/unit/cms_unittest.cc
index b0381db5c..673887d09 100644
--- a/src/test/unit/cms_unittest.cc
+++ b/src/test/unit/cms_unittest.cc
@@ -33,7 +33,7 @@ extern "C" {
     #include "fc/rc_modes.h"
     #include "fc/runtime_config.h"
     void cmsMenuOpen(void);
-    long cmsMenuBack(displayPort_t *pDisplay);
+    const void *cmsMenuBack(displayPort_t *pDisplay);
     uint16_t cmsHandleKey(displayPort_t *pDisplay, uint8_t key);
     extern CMS_Menu *currentMenu;    // Points to top entry of the current page
 }
@@ -71,8 +71,8 @@ TEST(CMSUnittest, TestCmsMenuExit0)
     cmsDisplayPortRegister(displayPort);
 
     cmsMenuOpen();
-    long exit = cmsMenuExit(displayPort, (void*)0);
-    EXPECT_EQ(0, exit);
+    const void *exit = cmsMenuExit(displayPort, (void*)0);
+    EXPECT_EQ(NULL, exit);
 }
 
 TEST(CMSUnittest, TestCmsMenuExit1)
@@ -82,8 +82,8 @@ TEST(CMSUnittest, TestCmsMenuExit1)
     cmsDisplayPortRegister(displayPort);
 
     cmsMenuOpen();
-    long exit = cmsMenuExit(displayPort, (void*)0);
-    EXPECT_EQ(0, exit);
+    const void *exit = cmsMenuExit(displayPort, (void*)0);
+    EXPECT_EQ(NULL, exit);
 }
 
 TEST(CMSUnittest, TestCmsMenuBack)
@@ -93,8 +93,8 @@ TEST(CMSUnittest, TestCmsMenuBack)
     cmsDisplayPortRegister(displayPort);
 
     cmsMenuOpen();
-    long exit = cmsMenuBack(displayPort);
-    EXPECT_EQ(0, exit);
+    const void *exit = cmsMenuBack(displayPort);
+    EXPECT_EQ(NULL, exit);
 }
 
 TEST(CMSUnittest, TestCmsMenuKey)