diff --git a/services/camera/libcameraservice/device3/Camera3IOStreamBase.cpp b/services/camera/libcameraservice/device3/Camera3IOStreamBase.cpp
index d662cc2..2257682 100644
--- a/services/camera/libcameraservice/device3/Camera3IOStreamBase.cpp
+++ b/services/camera/libcameraservice/device3/Camera3IOStreamBase.cpp
@@ -146,6 +146,13 @@
     // Inform tracker about becoming busy
     if (mDequeuedBufferCount == 0 && mState != STATE_IN_CONFIG &&
             mState != STATE_IN_RECONFIG) {
+        /**
+         * Avoid a spurious IDLE->ACTIVE->IDLE transition when using buffers
+         * before/after register_stream_buffers during initial configuration
+         * or re-configuration.
+         *
+         * TODO: IN_CONFIG and IN_RECONFIG checks only make sense for <HAL3.2
+         */
         sp<StatusTracker> statusTracker = mStatusTracker.promote();
         if (statusTracker != 0) {
             statusTracker->markComponentActive(mStatusId);
@@ -224,6 +231,13 @@
     mDequeuedBufferCount--;
     if (mDequeuedBufferCount == 0 && mState != STATE_IN_CONFIG &&
             mState != STATE_IN_RECONFIG) {
+        /**
+         * Avoid a spurious IDLE->ACTIVE->IDLE transition when using buffers
+         * before/after register_stream_buffers during initial configuration
+         * or re-configuration.
+         *
+         * TODO: IN_CONFIG and IN_RECONFIG checks only make sense for <HAL3.2
+         */
         ALOGV("%s: Stream %d: All buffers returned; now idle", __FUNCTION__,
                 mId);
         sp<StatusTracker> statusTracker = mStatusTracker.promote();
diff --git a/services/camera/libcameraservice/device3/Camera3Stream.cpp b/services/camera/libcameraservice/device3/Camera3Stream.cpp
index 70406f1..646f286 100644
--- a/services/camera/libcameraservice/device3/Camera3Stream.cpp
+++ b/services/camera/libcameraservice/device3/Camera3Stream.cpp
@@ -23,6 +23,8 @@
 #include "device3/Camera3Stream.h"
 #include "device3/StatusTracker.h"
 
+#include <cutils/properties.h>
+
 namespace android {
 
 namespace camera3 {
@@ -137,6 +139,7 @@
     if (mState == STATE_CONSTRUCTED) {
         mState = STATE_IN_CONFIG;
     } else { // mState == STATE_CONFIGURED
+        LOG_ALWAYS_FATAL_IF(mState != STATE_CONFIGURED, "Invalid state: 0x%x", mState);
         mState = STATE_IN_RECONFIG;
     }
 
@@ -223,6 +226,14 @@
     ATRACE_CALL();
     Mutex::Autolock l(mLock);
 
+    /**
+     * TODO: Check that the state is valid first.
+     *
+     * <HAL3.2 IN_CONFIG and IN_RECONFIG in addition to CONFIGURED.
+     * >= HAL3.2 CONFIGURED only
+     *
+     * Do this for getBuffer as well.
+     */
     status_t res = returnBufferLocked(buffer, timestamp);
     if (res == OK) {
         fireBufferListenersLocked(buffer, /*acquired*/false, /*output*/true);
@@ -314,12 +325,46 @@
 
 status_t Camera3Stream::registerBuffersLocked(camera3_device *hal3Device) {
     ATRACE_CALL();
+
+    /**
+     * >= CAMERA_DEVICE_API_VERSION_3_2:
+     *
+     * camera3_device_t->ops->register_stream_buffers() is not called and must
+     * be NULL.
+     */
+    if (hal3Device->common.version >= CAMERA_DEVICE_API_VERSION_3_2) {
+        ALOGV("%s: register_stream_buffers unused as of HAL3.2", __FUNCTION__);
+
+        /**
+         * Skip the NULL check if camera.dev.register_stream is 1.
+         *
+         * For development-validation purposes only.
+         *
+         * TODO: Remove the property check before shipping L (b/13914251).
+         */
+        char value[PROPERTY_VALUE_MAX] = { '\0', };
+        property_get("camera.dev.register_stream", value, "0");
+        int propInt = atoi(value);
+
+        if (propInt == 0 && hal3Device->ops->register_stream_buffers != NULL) {
+            ALOGE("%s: register_stream_buffers is deprecated in HAL3.2; "
+                    "must be set to NULL in camera3_device::ops", __FUNCTION__);
+            return INVALID_OPERATION;
+        } else {
+            ALOGD("%s: Skipping NULL check for deprecated register_stream_buffers");
+        }
+
+        return OK;
+    } else {
+        ALOGV("%s: register_stream_buffers using deprecated code path", __FUNCTION__);
+    }
+
     status_t res;
 
     size_t bufferCount = getBufferCountLocked();
 
     Vector<buffer_handle_t*> buffers;
-    buffers.insertAt(NULL, 0, bufferCount);
+    buffers.insertAt(/*prototype_item*/NULL, /*index*/0, bufferCount);
 
     camera3_stream_buffer_set bufferSet = camera3_stream_buffer_set();
     bufferSet.stream = this;
@@ -327,7 +372,7 @@
     bufferSet.buffers = buffers.editArray();
 
     Vector<camera3_stream_buffer_t> streamBuffers;
-    streamBuffers.insertAt(camera3_stream_buffer_t(), 0, bufferCount);
+    streamBuffers.insertAt(camera3_stream_buffer_t(), /*index*/0, bufferCount);
 
     // Register all buffers with the HAL. This means getting all the buffers
     // from the stream, providing them to the HAL with the
diff --git a/services/camera/libcameraservice/device3/Camera3Stream.h b/services/camera/libcameraservice/device3/Camera3Stream.h
index 6eeb721..766b772 100644
--- a/services/camera/libcameraservice/device3/Camera3Stream.h
+++ b/services/camera/libcameraservice/device3/Camera3Stream.h
@@ -82,6 +82,23 @@
  *    STATE_CONFIGURED     => STATE_CONSTRUCTED:
  *        When disconnect() is called after making sure stream is idle with
  *        waitUntilIdle().
+ *
+ * Status Tracking:
+ *    Each stream is tracked by StatusTracker as a separate component,
+ *    depending on the handed out buffer count. The state must be STATE_CONFIGURED
+ *    in order for the component to be marked.
+ *
+ *    It's marked in one of two ways:
+ *
+ *    - ACTIVE: One or more buffers have been handed out (with #getBuffer).
+ *    - IDLE: All buffers have been returned (with #returnBuffer), and their
+ *          respective release_fence(s) have been signaled.
+ *
+ *    A typical use case is output streams. When the HAL has any buffers
+ *    dequeued, the stream is marked ACTIVE. When the HAL returns all buffers
+ *    (e.g. if no capture requests are active), the stream is marked IDLE.
+ *    In this use case, the app consumer does not affect the component status.
+ *
  */
 class Camera3Stream :
         protected camera3_stream,