diff --git a/evs/1.0/default/EvsEnumerator.cpp b/evs/1.0/default/EvsEnumerator.cpp
index 9f38041..ba8da00 100644
--- a/evs/1.0/default/EvsEnumerator.cpp
+++ b/evs/1.0/default/EvsEnumerator.cpp
@@ -62,8 +62,7 @@
     return Void();
 }
 
-Return<void> EvsEnumerator::openCamera(const hidl_string& cameraId,
-                                             openCamera_cb callback) {
+Return<sp<IEvsCamera>> EvsEnumerator::openCamera(const hidl_string& cameraId) {
     ALOGD("openCamera");
 
     // Find the named camera
@@ -78,20 +77,18 @@
 
     if (!pRecord) {
         ALOGE("Requested camera %s not found", cameraId.c_str());
-        callback(nullptr);
+        return nullptr;
     }
     else if (pRecord->inUse) {
         ALOGE("Cannot open camera %s which is already in use", cameraId.c_str());
-        callback(nullptr);
+        return nullptr;
     }
     else {
         /* TODO(b/33492405):  Do this, When HIDL can give us back a recognizable pointer
         pRecord->inUse = true;
          */
-        callback(pRecord->pCamera);
+        return(pRecord->pCamera);
     }
-
-    return Void();
 }
 
 Return<void> EvsEnumerator::closeCamera(const ::android::sp<IEvsCamera>& camera) {
@@ -112,22 +109,20 @@
     return Void();
 }
 
-Return<void> EvsEnumerator::openDisplay(openDisplay_cb callback) {
+Return<sp<IEvsDisplay>> EvsEnumerator::openDisplay() {
     ALOGD("openDisplay");
 
     // If we already have a display active, then this request must be denied
     if (mActiveDisplay != nullptr) {
         ALOGW("Rejecting openDisplay request the display is already in use.");
-        callback(nullptr);
+        return nullptr;
     }
     else {
         // Create a new display interface and return it
         mActiveDisplay = new EvsDisplay();
         ALOGD("Returning new EvsDisplay object %p", mActiveDisplay.get());
-        callback(mActiveDisplay);
+        return mActiveDisplay;
     }
-
-    return Void();
 }
 
 Return<void> EvsEnumerator::closeDisplay(const ::android::sp<IEvsDisplay>& display) {
diff --git a/evs/1.0/default/EvsEnumerator.h b/evs/1.0/default/EvsEnumerator.h
index 69caa17..90df837 100644
--- a/evs/1.0/default/EvsEnumerator.h
+++ b/evs/1.0/default/EvsEnumerator.h
@@ -34,9 +34,9 @@
 public:
     // Methods from ::android::hardware::evs::V1_0::IEvsEnumerator follow.
     Return<void> getCameraList(getCameraList_cb _hidl_cb)  override;
-    Return<void> openCamera(const hidl_string& cameraId, openCamera_cb callback)  override;
+    Return<sp<IEvsCamera>> openCamera(const hidl_string& cameraId) override;
     Return<void> closeCamera(const ::android::sp<IEvsCamera>& carCamera)  override;
-    Return<void> openDisplay(openDisplay_cb callback)  override;
+    Return<sp<IEvsDisplay>> openDisplay()  override;
     Return<void> closeDisplay(const ::android::sp<IEvsDisplay>& display)  override;
 
     // Implementation details
diff --git a/gnss/1.0/default/Gnss.cpp b/gnss/1.0/default/Gnss.cpp
index 66be37e..5e6e65d 100644
--- a/gnss/1.0/default/Gnss.cpp
+++ b/gnss/1.0/default/Gnss.cpp
@@ -385,7 +385,7 @@
                                           preferredTimeMs) == 0);
 }
 
-Return<void> Gnss::getExtensionAGnssRil(getExtensionAGnssRil_cb _hidl_cb)  {
+Return<sp<IAGnssRil>> Gnss::getExtensionAGnssRil()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -397,11 +397,10 @@
             mGnssRil = new AGnssRil(agpsRilIface);
         }
     }
-    _hidl_cb(mGnssRil);
-    return Void();
+    return mGnssRil;
 }
 
-Return<void> Gnss::getExtensionGnssConfiguration(getExtensionGnssConfiguration_cb _hidl_cb)  {
+Return<sp<IGnssConfiguration>> Gnss::getExtensionGnssConfiguration()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -415,10 +414,9 @@
             mGnssConfig = new GnssConfiguration(gnssConfigIface);
         }
     }
-    _hidl_cb(mGnssConfig);
-    return Void();
+    return mGnssConfig;
 }
-Return<void> Gnss::getExtensionGnssGeofencing(getExtensionGnssGeofencing_cb _hidl_cb)  {
+Return<sp<IGnssGeofencing>> Gnss::getExtensionGnssGeofencing()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -433,11 +431,10 @@
         }
     }
 
-    _hidl_cb(mGnssGeofencingIface);
-    return Void();
+    return mGnssGeofencingIface;
 }
 
-Return<void> Gnss::getExtensionAGnss(getExtensionAGnss_cb _hidl_cb)  {
+Return<sp<IAGnss>> Gnss::getExtensionAGnss()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -449,11 +446,10 @@
             mAGnssIface = new AGnss(agpsIface);
         }
     }
-    _hidl_cb(mAGnssIface);
-    return Void();
+    return mAGnssIface;
 }
 
-Return<void> Gnss::getExtensionGnssNi(getExtensionGnssNi_cb _hidl_cb)  {
+Return<sp<IGnssNi>> Gnss::getExtensionGnssNi()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -465,11 +461,10 @@
             mGnssNi = new GnssNi(gpsNiIface);
         }
     }
-    _hidl_cb(mGnssNi);
-    return Void();
+    return mGnssNi;
 }
 
-Return<void> Gnss::getExtensionGnssMeasurement(getExtensionGnssMeasurement_cb _hidl_cb) {
+Return<sp<IGnssMeasurement>> Gnss::getExtensionGnssMeasurement() {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -483,12 +478,10 @@
             mGnssMeasurement = new GnssMeasurement(gpsMeasurementIface);
         }
     }
-    _hidl_cb(mGnssMeasurement);
-    return Void();
+    return mGnssMeasurement;
 }
 
-Return<void> Gnss::getExtensionGnssNavigationMessage(
-        getExtensionGnssNavigationMessage_cb _hidl_cb) {
+Return<sp<IGnssNavigationMessage>> Gnss::getExtensionGnssNavigationMessage() {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -504,11 +497,10 @@
         }
     }
 
-    _hidl_cb(mGnssNavigationMessage);
-    return Void();
+    return mGnssNavigationMessage;
 }
 
-Return<void> Gnss::getExtensionXtra(getExtensionXtra_cb _hidl_cb)  {
+Return<sp<IGnssXtra>> Gnss::getExtensionXtra()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -522,11 +514,10 @@
         }
     }
 
-    _hidl_cb(mGnssXtraIface);
-    return Void();
+    return mGnssXtraIface;
 }
 
-Return<void> Gnss::getExtensionGnssDebug(getExtensionGnssDebug_cb _hidl_cb)  {
+Return<sp<IGnssDebug>> Gnss::getExtensionGnssDebug()  {
     if (mGnssIface == nullptr) {
         ALOGE("%s: Gnss interface is unavailable", __func__);
     } else {
@@ -540,8 +531,7 @@
         }
     }
 
-    _hidl_cb(mGnssDebug);
-    return Void();
+    return mGnssDebug;
 }
 
 IGnss* HIDL_FETCH_IGnss(const char* hal) {
diff --git a/gnss/1.0/default/Gnss.h b/gnss/1.0/default/Gnss.h
index a2c8676..e12ac12 100644
--- a/gnss/1.0/default/Gnss.h
+++ b/gnss/1.0/default/Gnss.h
@@ -74,16 +74,15 @@
                                  uint32_t minIntervalMs,
                                  uint32_t preferredAccuracyMeters,
                                  uint32_t preferredTimeMs)  override;
-    Return<void> getExtensionAGnssRil(getExtensionAGnssRil_cb _hidl_cb) override;
-    Return<void> getExtensionGnssGeofencing(getExtensionGnssGeofencing_cb _hidl_cb)  override;
-    Return<void> getExtensionAGnss(getExtensionAGnss_cb _hidl_cb)  override;
-    Return<void> getExtensionGnssNi(getExtensionGnssNi_cb _hidl_cb)  override;
-    Return<void> getExtensionGnssMeasurement(getExtensionGnssMeasurement_cb _hidl_cb)  override;
-    Return<void> getExtensionGnssNavigationMessage(
-        getExtensionGnssNavigationMessage_cb _hidl_cb)  override;
-    Return<void> getExtensionXtra(getExtensionXtra_cb _hidl_cb)  override;
-    Return<void> getExtensionGnssDebug(getExtensionGnssDebug_cb _hidl_cb)  override;
-    Return<void> getExtensionGnssConfiguration(getExtensionGnssConfiguration_cb _hidl_cb) override;
+    Return<sp<IAGnssRil>> getExtensionAGnssRil() override;
+    Return<sp<IGnssGeofencing>> getExtensionGnssGeofencing() override;
+    Return<sp<IAGnss>> getExtensionAGnss() override;
+    Return<sp<IGnssNi>> getExtensionGnssNi() override;
+    Return<sp<IGnssMeasurement>> getExtensionGnssMeasurement() override;
+    Return<sp<IGnssNavigationMessage>> getExtensionGnssNavigationMessage() override;
+    Return<sp<IGnssXtra>> getExtensionXtra() override;
+    Return<sp<IGnssConfiguration>> getExtensionGnssConfiguration() override;
+    Return<sp<IGnssDebug>> getExtensionGnssDebug() override;
 
     /*
      * Callback methods to be passed into the conventional GNSS HAL by the default