diff --git a/libs/vr/libdisplay/Android.bp b/libs/vr/libdisplay/Android.bp
index 9c67881..8c354fb 100644
--- a/libs/vr/libdisplay/Android.bp
+++ b/libs/vr/libdisplay/Android.bp
@@ -16,8 +16,8 @@
     "display_client.cpp",
     "display_manager_client.cpp",
     "display_protocol.cpp",
-    "vsync_client.cpp",
     "shared_buffer_helpers.cpp",
+    "vsync_service.cpp",
 ]
 
 localIncludeFiles = [
diff --git a/libs/vr/libdisplay/include/private/dvr/vsync_client.h b/libs/vr/libdisplay/include/private/dvr/vsync_client.h
deleted file mode 100644
index 1eeb80e..0000000
--- a/libs/vr/libdisplay/include/private/dvr/vsync_client.h
+++ /dev/null
@@ -1,69 +0,0 @@
-#ifndef ANDROID_DVR_VSYNC_CLIENT_H_
-#define ANDROID_DVR_VSYNC_CLIENT_H_
-
-#include <stdint.h>
-
-#include <pdx/client.h>
-
-struct dvr_vsync_client {};
-
-namespace android {
-namespace dvr {
-
-/*
- * VSyncClient is a remote interface to the vsync service in displayd.
- * This class is used to wait for and retrieve information about the
- * display vsync.
- */
-class VSyncClient : public pdx::ClientBase<VSyncClient>,
-                    public dvr_vsync_client {
- public:
-  /*
-   * Wait for the next vsync signal.
-   * The timestamp (in ns) is written into *ts when ts is non-NULL.
-   */
-  int Wait(int64_t* timestamp_ns);
-
-  /*
-   * Returns the file descriptor used to communicate with the vsync system
-   * service or -1 on error.
-   */
-  int GetFd();
-
-  /*
-   * Clears the select/poll/epoll event so that subsequent calls to
-   * these will not signal until the next vsync.
-   */
-  int Acknowledge();
-
-  /*
-   * Get the timestamp of the last vsync event in ns. This call has
-   * the same side effect on events as Acknowledge(), which saves
-   * an IPC message.
-   */
-  int GetLastTimestamp(int64_t* timestamp_ns);
-
-  /*
-   * Get vsync scheduling info.
-   * Get the estimated timestamp of the next GPU lens warp preemption event in
-   * ns. Also returns the corresponding vsync count that the next lens warp
-   * operation will target. This call has the same side effect on events as
-   * Acknowledge(), which saves an IPC message.
-   */
-  int GetSchedInfo(int64_t* vsync_period_ns, int64_t* next_timestamp_ns,
-                   uint32_t* next_vsync_count);
-
- private:
-  friend BASE;
-
-  VSyncClient();
-  explicit VSyncClient(long timeout_ms);
-
-  VSyncClient(const VSyncClient&) = delete;
-  void operator=(const VSyncClient&) = delete;
-};
-
-}  // namespace dvr
-}  // namespace android
-
-#endif  // ANDROID_DVR_VSYNC_CLIENT_H_
diff --git a/libs/vr/libdisplay/include/private/dvr/vsync_service.h b/libs/vr/libdisplay/include/private/dvr/vsync_service.h
new file mode 100644
index 0000000..152464a
--- /dev/null
+++ b/libs/vr/libdisplay/include/private/dvr/vsync_service.h
@@ -0,0 +1,65 @@
+#ifndef ANDROID_DVR_VSYNC_SERVICE_H_
+#define ANDROID_DVR_VSYNC_SERVICE_H_
+
+#include <binder/IInterface.h>
+
+namespace android {
+namespace dvr {
+
+class IVsyncCallback : public IInterface {
+ public:
+  DECLARE_META_INTERFACE(VsyncCallback)
+
+  enum {
+    ON_VSYNC = IBinder::FIRST_CALL_TRANSACTION
+  };
+
+  virtual status_t onVsync(int64_t vsync_timestamp) = 0;
+};
+
+class BnVsyncCallback : public BnInterface<IVsyncCallback> {
+ public:
+  virtual status_t onTransact(uint32_t code, const Parcel& data,
+                              Parcel* reply, uint32_t flags = 0);
+};
+
+// Register a callback with IVsyncService to be notified of vsync events and
+// timestamps. There's also a shared memory vsync buffer defined in
+// dvr_shared_buffers.h. IVsyncService has advantages over the vsync shared
+// memory buffer that make it preferable in certain situations:
+//
+// 1. The shared memory buffer lifetime is controlled by VrCore. IVsyncService
+// is always available as long as surface flinger is running.
+//
+// 2. IVsyncService will make a binder callback when a vsync event occurs. This
+// allows the client to not write code to implement periodic "get the latest
+// vsync" calls, which is necessary with the vsync shared memory buffer.
+//
+// 3. The IVsyncService provides the real vsync timestamp reported by hardware
+// composer, whereas the vsync shared memory buffer only has predicted vsync
+// times.
+class IVsyncService : public IInterface {
+public:
+  DECLARE_META_INTERFACE(VsyncService)
+
+  static const char* GetServiceName() { return "vrflinger_vsync"; }
+
+  enum {
+    REGISTER_CALLBACK = IBinder::FIRST_CALL_TRANSACTION,
+    UNREGISTER_CALLBACK
+  };
+
+  virtual status_t registerCallback(const sp<IVsyncCallback> callback) = 0;
+  virtual status_t unregisterCallback(const sp<IVsyncCallback> callback) = 0;
+};
+
+class BnVsyncService : public BnInterface<IVsyncService> {
+ public:
+  virtual status_t onTransact(uint32_t code, const Parcel& data,
+                              Parcel* reply, uint32_t flags = 0);
+};
+
+}  // namespace dvr
+}  // namespace android
+
+#endif  // ANDROID_DVR_VSYNC_SERVICE_H_
diff --git a/libs/vr/libdisplay/vsync_client.cpp b/libs/vr/libdisplay/vsync_client.cpp
deleted file mode 100644
index bc6cf6c..0000000
--- a/libs/vr/libdisplay/vsync_client.cpp
+++ /dev/null
@@ -1,76 +0,0 @@
-#include "include/private/dvr/vsync_client.h"
-
-#include <log/log.h>
-
-#include <pdx/default_transport/client_channel_factory.h>
-#include <private/dvr/display_protocol.h>
-
-using android::dvr::display::VSyncProtocol;
-using android::pdx::Transaction;
-
-namespace android {
-namespace dvr {
-
-VSyncClient::VSyncClient(long timeout_ms)
-    : BASE(pdx::default_transport::ClientChannelFactory::Create(
-               VSyncProtocol::kClientPath),
-           timeout_ms) {}
-
-VSyncClient::VSyncClient()
-    : BASE(pdx::default_transport::ClientChannelFactory::Create(
-          VSyncProtocol::kClientPath)) {}
-
-int VSyncClient::Wait(int64_t* timestamp_ns) {
-  auto status = InvokeRemoteMethod<VSyncProtocol::Wait>();
-  if (!status) {
-    ALOGE("VSyncClient::Wait: Failed to wait for vsync: %s",
-          status.GetErrorMessage().c_str());
-    return -status.error();
-  }
-
-  if (timestamp_ns != nullptr) {
-    *timestamp_ns = status.get();
-  }
-  return 0;
-}
-
-int VSyncClient::GetFd() { return event_fd(); }
-
-int VSyncClient::GetLastTimestamp(int64_t* timestamp_ns) {
-  auto status = InvokeRemoteMethod<VSyncProtocol::GetLastTimestamp>();
-  if (!status) {
-    ALOGE("VSyncClient::GetLastTimestamp: Failed to get vsync timestamp: %s",
-          status.GetErrorMessage().c_str());
-    return -status.error();
-  }
-  *timestamp_ns = status.get();
-  return 0;
-}
-
-int VSyncClient::GetSchedInfo(int64_t* vsync_period_ns, int64_t* timestamp_ns,
-                              uint32_t* next_vsync_count) {
-  if (!vsync_period_ns || !timestamp_ns || !next_vsync_count)
-    return -EINVAL;
-
-  auto status = InvokeRemoteMethod<VSyncProtocol::GetSchedInfo>();
-  if (!status) {
-    ALOGE("VSyncClient::GetSchedInfo:: Failed to get warp timestamp: %s",
-          status.GetErrorMessage().c_str());
-    return -status.error();
-  }
-
-  *vsync_period_ns = status.get().vsync_period_ns;
-  *timestamp_ns = status.get().timestamp_ns;
-  *next_vsync_count = status.get().next_vsync_count;
-  return 0;
-}
-
-int VSyncClient::Acknowledge() {
-  auto status = InvokeRemoteMethod<VSyncProtocol::Acknowledge>();
-  ALOGE_IF(!status, "VSuncClient::Acknowledge: Failed to ack vsync because: %s",
-           status.GetErrorMessage().c_str());
-  return ReturnStatusOrError(status);
-}
-
-}  // namespace dvr
-}  // namespace android
diff --git a/libs/vr/libdisplay/vsync_service.cpp b/libs/vr/libdisplay/vsync_service.cpp
new file mode 100644
index 0000000..43b1196
--- /dev/null
+++ b/libs/vr/libdisplay/vsync_service.cpp
@@ -0,0 +1,146 @@
+#include "include/private/dvr/vsync_service.h"
+
+#include <binder/Parcel.h>
+#include <log/log.h>
+
+namespace android {
+namespace dvr {
+
+status_t BnVsyncCallback::onTransact(
+    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) {
+  switch (code) {
+    case ON_VSYNC: {
+      CHECK_INTERFACE(IVsyncCallback, data, reply);
+      int64_t vsync_timestamp = 0;
+      status_t result = data.readInt64(&vsync_timestamp);
+      if (result != NO_ERROR) {
+        ALOGE("onVsync failed to readInt64: %d", result);
+        return result;
+      }
+      onVsync(vsync_timestamp);
+      return NO_ERROR;
+    }
+    default: {
+      return BBinder::onTransact(code, data, reply, flags);
+    }
+  }
+}
+
+class BpVsyncCallback : public BpInterface<IVsyncCallback> {
+public:
+  explicit BpVsyncCallback(const sp<IBinder>& impl)
+      : BpInterface<IVsyncCallback>(impl) {}
+  virtual ~BpVsyncCallback() {}
+
+  virtual status_t onVsync(int64_t vsync_timestamp) {
+    Parcel data, reply;
+    status_t result = data.writeInterfaceToken(
+        IVsyncCallback::getInterfaceDescriptor());
+    if (result != NO_ERROR) {
+      ALOGE("onVsync failed to writeInterfaceToken: %d", result);
+      return result;
+    }
+    result = data.writeInt64(vsync_timestamp);
+    if (result != NO_ERROR) {
+      ALOGE("onVsync failed to writeInt64: %d", result);
+      return result;
+    }
+    result = remote()->transact(
+        BnVsyncCallback::ON_VSYNC, data, &reply, TF_ONE_WAY);
+    if (result != NO_ERROR) {
+      ALOGE("onVsync failed to transact: %d", result);
+      return result;
+    }
+    return result;
+  }
+};
+
+IMPLEMENT_META_INTERFACE(VsyncCallback, "android.dvr.IVsyncCallback");
+
+
+status_t BnVsyncService::onTransact(
+    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) {
+  switch (code) {
+    case REGISTER_CALLBACK: {
+      CHECK_INTERFACE(IVsyncService, data, reply);
+      sp<IBinder> callback;
+      status_t result = data.readStrongBinder(&callback);
+      if (result != NO_ERROR) {
+        ALOGE("registerCallback failed to readStrongBinder: %d", result);
+        return result;
+      }
+      registerCallback(interface_cast<IVsyncCallback>(callback));
+      return NO_ERROR;
+    }
+    case UNREGISTER_CALLBACK: {
+      CHECK_INTERFACE(IVsyncService, data, reply);
+      sp<IBinder> callback;
+      status_t result = data.readStrongBinder(&callback);
+      if (result != NO_ERROR) {
+        ALOGE("unregisterCallback failed to readStrongBinder: %d", result);
+        return result;
+      }
+      unregisterCallback(interface_cast<IVsyncCallback>(callback));
+      return NO_ERROR;
+    }
+    default: {
+      return BBinder::onTransact(code, data, reply, flags);
+    }
+  }
+}
+
+class BpVsyncService : public BpInterface<IVsyncService> {
+public:
+  explicit BpVsyncService(const sp<IBinder>& impl)
+      : BpInterface<IVsyncService>(impl) {}
+  virtual ~BpVsyncService() {}
+
+  virtual status_t registerCallback(const sp<IVsyncCallback> callback) {
+    Parcel data, reply;
+    status_t result = data.writeInterfaceToken(
+        IVsyncService::getInterfaceDescriptor());
+    if (result != NO_ERROR) {
+      ALOGE("registerCallback failed to writeInterfaceToken: %d", result);
+      return result;
+    }
+    result = data.writeStrongBinder(IInterface::asBinder(callback));
+    if (result != NO_ERROR) {
+      ALOGE("registerCallback failed to writeStrongBinder: %d", result);
+      return result;
+    }
+    result = remote()->transact(
+        BnVsyncService::REGISTER_CALLBACK, data, &reply);
+    if (result != NO_ERROR) {
+      ALOGE("registerCallback failed to transact: %d", result);
+      return result;
+    }
+    return result;
+  }
+
+  virtual status_t unregisterCallback(const sp<IVsyncCallback> callback) {
+    Parcel data, reply;
+    status_t result = data.writeInterfaceToken(
+        IVsyncService::getInterfaceDescriptor());
+    if (result != NO_ERROR) {
+      ALOGE("unregisterCallback failed to writeInterfaceToken: %d", result);
+      return result;
+    }
+    result = data.writeStrongBinder(IInterface::asBinder(callback));
+    if (result != NO_ERROR) {
+      ALOGE("unregisterCallback failed to writeStrongBinder: %d", result);
+      return result;
+    }
+    result = remote()->transact(
+        BnVsyncService::UNREGISTER_CALLBACK, data, &reply);
+    if (result != NO_ERROR) {
+      ALOGE("unregisterCallback failed to transact: %d", result);
+      return result;
+    }
+    return result;
+  }
+};
+
+IMPLEMENT_META_INTERFACE(VsyncService, "android.dvr.IVsyncService");
+
+}  // namespace dvr
+}  // namespace android
diff --git a/libs/vr/libdvr/Android.bp b/libs/vr/libdvr/Android.bp
index 00e4d4e..3829951 100644
--- a/libs/vr/libdvr/Android.bp
+++ b/libs/vr/libdvr/Android.bp
@@ -44,7 +44,6 @@
     "dvr_pose.cpp",
     "dvr_surface.cpp",
     "dvr_tracking.cpp",
-    "dvr_vsync.cpp",
 ]
 
 static_libs = [
diff --git a/libs/vr/libdvr/dvr_vsync.cpp b/libs/vr/libdvr/dvr_vsync.cpp
deleted file mode 100644
index 099240e..0000000
--- a/libs/vr/libdvr/dvr_vsync.cpp
+++ /dev/null
@@ -1,33 +0,0 @@
-#include "include/dvr/dvr_vsync.h"
-
-#include <utils/Log.h>
-
-#include <private/dvr/vsync_client.h>
-
-extern "C" {
-
-struct DvrVSyncClient {
-  std::unique_ptr<android::dvr::VSyncClient> client;
-};
-
-int dvrVSyncClientCreate(DvrVSyncClient** client_out) {
-  auto client = android::dvr::VSyncClient::Create();
-  if (!client) {
-    ALOGE("dvrVSyncClientCreate: Failed to create vsync client!");
-    return -EIO;
-  }
-
-  *client_out = new DvrVSyncClient{std::move(client)};
-  return 0;
-}
-
-void dvrVSyncClientDestroy(DvrVSyncClient* client) { delete client; }
-
-int dvrVSyncClientGetSchedInfo(DvrVSyncClient* client, int64_t* vsync_period_ns,
-                               int64_t* next_timestamp_ns,
-                               uint32_t* next_vsync_count) {
-  return client->client->GetSchedInfo(vsync_period_ns, next_timestamp_ns,
-                                      next_vsync_count);
-}
-
-}  // extern "C"
diff --git a/libs/vr/libdvr/include/dvr/dvr_api_entries.h b/libs/vr/libdvr/include/dvr/dvr_api_entries.h
index 6620a37..3006b61 100644
--- a/libs/vr/libdvr/include/dvr/dvr_api_entries.h
+++ b/libs/vr/libdvr/include/dvr/dvr_api_entries.h
@@ -85,9 +85,9 @@
 DVR_V1_API_ENTRY(ReadBufferQueueHandleEvents);
 
 // V-Sync client
-DVR_V1_API_ENTRY(VSyncClientCreate);
-DVR_V1_API_ENTRY(VSyncClientDestroy);
-DVR_V1_API_ENTRY(VSyncClientGetSchedInfo);
+DVR_V1_API_ENTRY_DEPRECATED(VSyncClientCreate);
+DVR_V1_API_ENTRY_DEPRECATED(VSyncClientDestroy);
+DVR_V1_API_ENTRY_DEPRECATED(VSyncClientGetSchedInfo);
 
 // Display surface
 DVR_V1_API_ENTRY(SurfaceCreate);
diff --git a/libs/vr/libdvr/include/dvr/dvr_deleter.h b/libs/vr/libdvr/include/dvr/dvr_deleter.h
index 943384f..fe59d1f 100644
--- a/libs/vr/libdvr/include/dvr/dvr_deleter.h
+++ b/libs/vr/libdvr/include/dvr/dvr_deleter.h
@@ -20,7 +20,6 @@
 typedef struct DvrSurface DvrSurface;
 typedef struct DvrHwcClient DvrHwcClient;
 typedef struct DvrHwcFrame DvrHwcFrame;
-typedef struct DvrVSyncClient DvrVSyncClient;
 
 void dvrBufferDestroy(DvrBuffer* buffer);
 void dvrReadBufferDestroy(DvrReadBuffer* read_buffer);
@@ -32,7 +31,6 @@
 void dvrSurfaceDestroy(DvrSurface* surface);
 void dvrHwcClientDestroy(DvrHwcClient* client);
 void dvrHwcFrameDestroy(DvrHwcFrame* frame);
-void dvrVSyncClientDestroy(DvrVSyncClient* client);
 
 __END_DECLS
 
@@ -55,7 +53,6 @@
   void operator()(DvrSurface* p) { dvrSurfaceDestroy(p); }
   void operator()(DvrHwcClient* p) { dvrHwcClientDestroy(p); }
   void operator()(DvrHwcFrame* p) { dvrHwcFrameDestroy(p); }
-  void operator()(DvrVSyncClient* p) { dvrVSyncClientDestroy(p); }
 };
 
 // Helper to define unique pointers for DVR object types.
@@ -73,7 +70,6 @@
 using UniqueDvrSurface = MakeUniqueDvrPointer<DvrSurface>;
 using UniqueDvrHwcClient = MakeUniqueDvrPointer<DvrHwcClient>;
 using UniqueDvrHwcFrame = MakeUniqueDvrPointer<DvrHwcFrame>;
-using UniqueDvrVSyncClient = MakeUniqueDvrPointer<DvrVSyncClient>;
 
 // TODO(eieio): Add an adapter for std::shared_ptr that injects the deleter into
 // the relevant constructors.
diff --git a/libs/vr/libdvr/include/dvr/dvr_vsync.h b/libs/vr/libdvr/include/dvr/dvr_vsync.h
index 87fdf31..498bb5c 100644
--- a/libs/vr/libdvr/include/dvr/dvr_vsync.h
+++ b/libs/vr/libdvr/include/dvr/dvr_vsync.h
@@ -6,8 +6,6 @@
 
 __BEGIN_DECLS
 
-typedef struct DvrVSyncClient DvrVSyncClient;
-
 // Represents a vsync sample. The size of this struct is 32 bytes.
 typedef struct __attribute__((packed, aligned(16))) DvrVsync {
   // The timestamp for the last vsync in nanoseconds.
@@ -29,19 +27,6 @@
   uint8_t padding[8];
 } DvrVsync;
 
-// Creates a new client to the system vsync service.
-int dvrVSyncClientCreate(DvrVSyncClient** client_out);
-
-// Destroys the vsync client.
-void dvrVSyncClientDestroy(DvrVSyncClient* client);
-
-// Get the estimated timestamp of the next GPU lens warp preemption event in/
-// ns. Also returns the corresponding vsync count that the next lens warp
-// operation will target.
-int dvrVSyncClientGetSchedInfo(DvrVSyncClient* client, int64_t* vsync_period_ns,
-                               int64_t* next_timestamp_ns,
-                               uint32_t* next_vsync_count);
-
 __END_DECLS
 
 #endif  // ANDROID_DVR_VSYNC_H_
diff --git a/libs/vr/libvrflinger/Android.bp b/libs/vr/libvrflinger/Android.bp
index 6f3f1d6..776dd8e 100644
--- a/libs/vr/libvrflinger/Android.bp
+++ b/libs/vr/libvrflinger/Android.bp
@@ -20,7 +20,6 @@
     "display_surface.cpp",
     "hardware_composer.cpp",
     "vr_flinger.cpp",
-    "vsync_service.cpp",
 ]
 
 includeFiles = [ "include" ]
diff --git a/libs/vr/libvrflinger/display_service.h b/libs/vr/libvrflinger/display_service.h
index 3090bd1..6fad58e 100644
--- a/libs/vr/libvrflinger/display_service.h
+++ b/libs/vr/libvrflinger/display_service.h
@@ -60,11 +60,6 @@
   void SetDisplayConfigurationUpdateNotifier(
       DisplayConfigurationUpdateNotifier notifier);
 
-  using VSyncCallback = HardwareComposer::VSyncCallback;
-  void SetVSyncCallback(VSyncCallback callback) {
-    hardware_composer_.SetVSyncCallback(callback);
-  }
-
   void GrantDisplayOwnership() { hardware_composer_.Enable(); }
   void SeizeDisplayOwnership() { hardware_composer_.Disable(); }
   void OnBootFinished() { hardware_composer_.OnBootFinished(); }
diff --git a/libs/vr/libvrflinger/hardware_composer.cpp b/libs/vr/libvrflinger/hardware_composer.cpp
index 44ce78c..e98d592 100644
--- a/libs/vr/libvrflinger/hardware_composer.cpp
+++ b/libs/vr/libvrflinger/hardware_composer.cpp
@@ -1,5 +1,6 @@
 #include "hardware_composer.h"
 
+#include <binder/IServiceManager.h>
 #include <cutils/properties.h>
 #include <cutils/sched_policy.h>
 #include <fcntl.h>
@@ -52,6 +53,10 @@
 
 const char kUseExternalDisplayProperty[] = "persist.vr.use_external_display";
 
+// Surface flinger uses "VSYNC-sf" and "VSYNC-app" for its version of these
+// events. Name ours similarly.
+const char kVsyncTraceEventName[] = "VSYNC-vrflinger";
+
 // How long to wait after boot finishes before we turn the display off.
 constexpr int kBootFinishedDisplayOffTimeoutSec = 10;
 
@@ -131,6 +136,7 @@
   UpdatePostThreadState(PostThreadState::Quit, true);
   if (post_thread_.joinable())
     post_thread_.join();
+  composer_callback_->SetVsyncService(nullptr);
 }
 
 bool HardwareComposer::Initialize(
@@ -147,6 +153,13 @@
 
   primary_display_ = GetDisplayParams(composer, primary_display_id, true);
 
+  vsync_service_ = new VsyncService;
+  sp<IServiceManager> sm(defaultServiceManager());
+  auto result = sm->addService(String16(VsyncService::GetServiceName()),
+      vsync_service_, false);
+  LOG_ALWAYS_FATAL_IF(result != android::OK,
+      "addService(%s) failed", VsyncService::GetServiceName());
+
   post_thread_event_fd_.Reset(eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK));
   LOG_ALWAYS_FATAL_IF(
       !post_thread_event_fd_,
@@ -223,6 +236,7 @@
   LOG_ALWAYS_FATAL_IF(!composer_callback_->GotFirstHotplug(),
       "Registered composer callback but didn't get hotplug for primary"
       " display");
+  composer_callback_->SetVsyncService(vsync_service_);
 }
 
 void HardwareComposer::OnPostThreadResumed() {
@@ -242,7 +256,10 @@
   // Standalones only create the composer client once and then use SetPowerMode
   // to control the screen on pause/resume.
   if (!is_standalone_device_) {
-    composer_callback_ = nullptr;
+    if (composer_callback_ != nullptr) {
+      composer_callback_->SetVsyncService(nullptr);
+      composer_callback_ = nullptr;
+    }
     composer_.reset(nullptr);
   } else {
     EnableDisplay(*target_display_, false);
@@ -336,7 +353,6 @@
   // According to the documentation, this fence is signaled at the time of
   // vsync/DMA for physical displays.
   if (error == HWC::Error::None) {
-    ATRACE_INT("HardwareComposer: VsyncFence", present_fence);
     retire_fence_fds_.emplace_back(present_fence);
   } else {
     ATRACE_INT("HardwareComposer: PresentResult", error);
@@ -775,6 +791,11 @@
       std::unique_lock<std::mutex> lock(post_thread_mutex_);
       ALOGI("HardwareComposer::PostThread: Entering quiescent state.");
 
+      if (was_running) {
+        vsync_trace_parity_ = false;
+        ATRACE_INT(kVsyncTraceEventName, 0);
+      }
+
       // Tear down resources.
       OnPostThreadPaused();
       was_running = false;
@@ -848,6 +869,9 @@
       vsync_timestamp = status.get();
     }
 
+    vsync_trace_parity_ = !vsync_trace_parity_;
+    ATRACE_INT(kVsyncTraceEventName, vsync_trace_parity_ ? 1 : 0);
+
     // Advance the vsync counter only if the system is keeping up with hardware
     // vsync to give clients an indication of the delays.
     if (vsync_prediction_interval_ == 1)
@@ -867,11 +891,6 @@
       vsync_ring_->Publish(vsync);
     }
 
-    // Signal all of the vsync clients. Because absolute time is used for the
-    // wakeup time below, this can take a little time if necessary.
-    if (vsync_callback_)
-      vsync_callback_(vsync_timestamp, /*frame_time_estimate*/ 0, vsync_count_);
-
     {
       // Sleep until shortly before vsync.
       ATRACE_NAME("sleep");
@@ -1063,8 +1082,45 @@
            layers_.size());
 }
 
-void HardwareComposer::SetVSyncCallback(VSyncCallback callback) {
-  vsync_callback_ = callback;
+std::vector<sp<IVsyncCallback>>::const_iterator
+HardwareComposer::VsyncService::FindCallback(
+    const sp<IVsyncCallback>& callback) const {
+  sp<IBinder> binder = IInterface::asBinder(callback);
+  return std::find_if(callbacks_.cbegin(), callbacks_.cend(),
+                      [&](const sp<IVsyncCallback>& callback) {
+                        return IInterface::asBinder(callback) == binder;
+                      });
+}
+
+status_t HardwareComposer::VsyncService::registerCallback(
+    const sp<IVsyncCallback> callback) {
+  std::lock_guard<std::mutex> autolock(mutex_);
+  if (FindCallback(callback) == callbacks_.cend()) {
+    callbacks_.push_back(callback);
+  }
+  return NO_ERROR;
+}
+
+status_t HardwareComposer::VsyncService::unregisterCallback(
+    const sp<IVsyncCallback> callback) {
+  std::lock_guard<std::mutex> autolock(mutex_);
+  auto iter = FindCallback(callback);
+  if (iter != callbacks_.cend()) {
+    callbacks_.erase(iter);
+  }
+  return NO_ERROR;
+}
+
+void HardwareComposer::VsyncService::OnVsync(int64_t vsync_timestamp) {
+  ATRACE_NAME("VsyncService::OnVsync");
+  std::lock_guard<std::mutex> autolock(mutex_);
+  for (auto iter = callbacks_.begin(); iter != callbacks_.end();) {
+    if ((*iter)->onVsync(vsync_timestamp) == android::DEAD_OBJECT) {
+      iter = callbacks_.erase(iter);
+    } else {
+      ++iter;
+    }
+  }
 }
 
 Return<void> HardwareComposer::ComposerCallback::onHotplug(
@@ -1123,16 +1179,26 @@
 
 Return<void> HardwareComposer::ComposerCallback::onVsync(Hwc2::Display display,
                                                          int64_t timestamp) {
+  TRACE_FORMAT("vsync_callback|display=%" PRIu64 ";timestamp=%" PRId64 "|",
+               display, timestamp);
+  std::lock_guard<std::mutex> lock(mutex_);
   DisplayInfo* display_info = GetDisplayInfo(display);
   if (display_info) {
-    TRACE_FORMAT("vsync_callback|display=%" PRIu64 ";timestamp=%" PRId64 "|",
-                 display, timestamp);
     display_info->callback_vsync_timestamp = timestamp;
   }
+  if (primary_display_.id == display && vsync_service_ != nullptr) {
+    vsync_service_->OnVsync(timestamp);
+  }
 
   return Void();
 }
 
+void HardwareComposer::ComposerCallback::SetVsyncService(
+    const sp<VsyncService>& vsync_service) {
+  std::lock_guard<std::mutex> lock(mutex_);
+  vsync_service_ = vsync_service;
+}
+
 HardwareComposer::ComposerCallback::Displays
 HardwareComposer::ComposerCallback::GetDisplays() {
   std::lock_guard<std::mutex> lock(mutex_);
@@ -1149,6 +1215,7 @@
 
 Status<int64_t> HardwareComposer::ComposerCallback::GetVsyncTime(
     hwc2_display_t display) {
+  std::lock_guard<std::mutex> autolock(mutex_);
   DisplayInfo* display_info = GetDisplayInfo(display);
   if (!display_info) {
     ALOGW("Attempt to get vsync time for unknown display %" PRIu64, display);
@@ -1160,7 +1227,6 @@
   if (!event_fd) {
     // Fall back to returning the last timestamp returned by the vsync
     // callback.
-    std::lock_guard<std::mutex> autolock(mutex_);
     return display_info->callback_vsync_timestamp;
   }
 
diff --git a/libs/vr/libvrflinger/hardware_composer.h b/libs/vr/libvrflinger/hardware_composer.h
index 1d8d463..80fa7ac 100644
--- a/libs/vr/libvrflinger/hardware_composer.h
+++ b/libs/vr/libvrflinger/hardware_composer.h
@@ -24,6 +24,7 @@
 #include <pdx/rpc/variant.h>
 #include <private/dvr/buffer_hub_client.h>
 #include <private/dvr/shared_buffer_helpers.h>
+#include <private/dvr/vsync_service.h>
 
 #include "acquired_buffer.h"
 #include "display_surface.h"
@@ -300,8 +301,6 @@
 // will access the state and whether it needs to be synchronized.
 class HardwareComposer {
  public:
-  // Type for vsync callback.
-  using VSyncCallback = std::function<void(int64_t, int64_t, uint32_t)>;
   using RequestDisplayCallback = std::function<void(bool)>;
 
   HardwareComposer();
@@ -325,8 +324,6 @@
 
   std::string Dump();
 
-  void SetVSyncCallback(VSyncCallback callback);
-
   const DisplayParams& GetPrimaryDisplayParams() const {
     return primary_display_;
   }
@@ -350,6 +347,18 @@
   // on/off. Returns true on success, false on failure.
   bool EnableDisplay(const DisplayParams& display, bool enabled);
 
+  class VsyncService : public BnVsyncService {
+   public:
+    status_t registerCallback(const sp<IVsyncCallback> callback) override;
+    status_t unregisterCallback(const sp<IVsyncCallback> callback) override;
+    void OnVsync(int64_t vsync_timestamp);
+   private:
+    std::vector<sp<IVsyncCallback>>::const_iterator FindCallback(
+        const sp<IVsyncCallback>& callback) const;
+    std::mutex mutex_;
+    std::vector<sp<IVsyncCallback>> callbacks_;
+  };
+
   class ComposerCallback : public Hwc2::IComposerCallback {
    public:
     ComposerCallback() = default;
@@ -360,6 +369,7 @@
                                    int64_t timestamp) override;
 
     bool GotFirstHotplug() { return got_first_hotplug_; }
+    void SetVsyncService(const sp<VsyncService>& vsync_service);
 
     struct Displays {
       hwc2_display_t primary_display = 0;
@@ -385,6 +395,7 @@
     DisplayInfo primary_display_;
     std::optional<DisplayInfo> external_display_;
     bool external_display_was_hotplugged_ = false;
+    sp<VsyncService> vsync_service_;
   };
 
   HWC::Error Validate(hwc2_display_t display);
@@ -484,9 +495,6 @@
   // vector must be sorted by surface_id in ascending order.
   std::vector<Layer> layers_;
 
-  // Handler to hook vsync events outside of this class.
-  VSyncCallback vsync_callback_;
-
   // The layer posting thread. This thread wakes up a short time before vsync to
   // hand buffers to hardware composer.
   std::thread post_thread_;
@@ -534,6 +542,9 @@
   DvrConfig post_thread_config_;
   std::mutex shared_config_mutex_;
 
+  bool vsync_trace_parity_ = false;
+  sp<VsyncService> vsync_service_;
+
   static constexpr int kPostThreadInterrupted = 1;
 
   HardwareComposer(const HardwareComposer&) = delete;
diff --git a/libs/vr/libvrflinger/vr_flinger.cpp b/libs/vr/libvrflinger/vr_flinger.cpp
index 26aed4f..b57383a 100644
--- a/libs/vr/libvrflinger/vr_flinger.cpp
+++ b/libs/vr/libvrflinger/vr_flinger.cpp
@@ -23,7 +23,6 @@
 #include "DisplayHardware/ComposerHal.h"
 #include "display_manager_service.h"
 #include "display_service.h"
-#include "vsync_service.h"
 
 namespace android {
 namespace dvr {
@@ -85,16 +84,6 @@
   CHECK_ERROR(!service, error, "Failed to create display manager service.");
   dispatcher_->AddService(service);
 
-  service = android::dvr::VSyncService::Create();
-  CHECK_ERROR(!service, error, "Failed to create vsync service.");
-  dispatcher_->AddService(service);
-
-  display_service_->SetVSyncCallback(
-      std::bind(&android::dvr::VSyncService::VSyncEvent,
-                std::static_pointer_cast<android::dvr::VSyncService>(service),
-                std::placeholders::_1, std::placeholders::_2,
-                std::placeholders::_3));
-
   dispatcher_thread_ = std::thread([this]() {
     prctl(PR_SET_NAME, reinterpret_cast<unsigned long>("VrDispatch"), 0, 0, 0);
     ALOGI("Entering message loop.");
diff --git a/libs/vr/libvrflinger/vsync_service.cpp b/libs/vr/libvrflinger/vsync_service.cpp
deleted file mode 100644
index b8d8b08..0000000
--- a/libs/vr/libvrflinger/vsync_service.cpp
+++ /dev/null
@@ -1,212 +0,0 @@
-#include "vsync_service.h"
-
-#include <hardware/hwcomposer.h>
-#include <log/log.h>
-#include <poll.h>
-#include <sys/prctl.h>
-#include <time.h>
-#include <utils/Trace.h>
-
-#include <dvr/dvr_display_types.h>
-#include <pdx/default_transport/service_endpoint.h>
-#include <private/dvr/clock_ns.h>
-#include <private/dvr/display_protocol.h>
-
-using android::dvr::display::VSyncProtocol;
-using android::dvr::display::VSyncSchedInfo;
-using android::pdx::Channel;
-using android::pdx::Message;
-using android::pdx::MessageInfo;
-using android::pdx::default_transport::Endpoint;
-using android::pdx::rpc::DispatchRemoteMethod;
-
-namespace android {
-namespace dvr {
-
-VSyncService::VSyncService()
-    : BASE("VSyncService", Endpoint::Create(VSyncProtocol::kClientPath)),
-      last_vsync_(0),
-      current_vsync_(0),
-      compositor_time_ns_(0),
-      current_vsync_count_(0) {}
-
-VSyncService::~VSyncService() {}
-
-void VSyncService::VSyncEvent(int64_t timestamp_ns,
-                              int64_t compositor_time_ns,
-                              uint32_t vsync_count) {
-  ATRACE_NAME("VSyncService::VSyncEvent");
-  std::lock_guard<std::mutex> autolock(mutex_);
-
-  last_vsync_ = current_vsync_;
-  current_vsync_ = timestamp_ns;
-  compositor_time_ns_ = compositor_time_ns;
-  current_vsync_count_ = vsync_count;
-
-  NotifyWaiters();
-  UpdateClients();
-}
-
-std::shared_ptr<Channel> VSyncService::OnChannelOpen(pdx::Message& message) {
-  const MessageInfo& info = message.GetInfo();
-
-  auto client = std::make_shared<VSyncChannel>(*this, info.pid, info.cid);
-  AddClient(client);
-
-  return client;
-}
-
-void VSyncService::OnChannelClose(pdx::Message& /*message*/,
-                                  const std::shared_ptr<Channel>& channel) {
-  auto client = std::static_pointer_cast<VSyncChannel>(channel);
-  if (!client) {
-    ALOGW("WARNING: VSyncChannel was NULL!!!\n");
-    return;
-  }
-
-  RemoveClient(client);
-}
-
-void VSyncService::AddWaiter(pdx::Message& message) {
-  std::lock_guard<std::mutex> autolock(mutex_);
-  std::unique_ptr<VSyncWaiter> waiter(new VSyncWaiter(message));
-  waiters_.push_back(std::move(waiter));
-}
-
-void VSyncService::AddClient(const std::shared_ptr<VSyncChannel>& client) {
-  std::lock_guard<std::mutex> autolock(mutex_);
-  clients_.push_back(client);
-}
-
-void VSyncService::RemoveClient(const std::shared_ptr<VSyncChannel>& client) {
-  std::lock_guard<std::mutex> autolock(mutex_);
-  clients_.remove(client);
-}
-
-// Private. Assumes mutex is held.
-void VSyncService::NotifyWaiters() {
-  ATRACE_NAME("VSyncService::NotifyWaiters");
-  auto first = waiters_.begin();
-  auto last = waiters_.end();
-
-  while (first != last) {
-    (*first)->Notify(current_vsync_);
-    waiters_.erase(first++);
-  }
-}
-
-// Private. Assumes mutex is held.
-void VSyncService::UpdateClients() {
-  ATRACE_NAME("VSyncService::UpdateClients");
-  auto first = clients_.begin();
-  auto last = clients_.end();
-
-  while (first != last) {
-    (*first)->Signal();
-    first++;
-  }
-}
-
-pdx::Status<void> VSyncService::HandleMessage(pdx::Message& message) {
-  ATRACE_NAME("VSyncService::HandleMessage");
-  switch (message.GetOp()) {
-    case VSyncProtocol::Wait::Opcode:
-      AddWaiter(message);
-      return {};
-
-    case VSyncProtocol::GetLastTimestamp::Opcode:
-      DispatchRemoteMethod<VSyncProtocol::GetLastTimestamp>(
-          *this, &VSyncService::OnGetLastTimestamp, message);
-      return {};
-
-    case VSyncProtocol::GetSchedInfo::Opcode:
-      DispatchRemoteMethod<VSyncProtocol::GetSchedInfo>(
-          *this, &VSyncService::OnGetSchedInfo, message);
-      return {};
-
-    case VSyncProtocol::Acknowledge::Opcode:
-      DispatchRemoteMethod<VSyncProtocol::Acknowledge>(
-          *this, &VSyncService::OnAcknowledge, message);
-      return {};
-
-    default:
-      return Service::HandleMessage(message);
-  }
-}
-
-pdx::Status<int64_t> VSyncService::OnGetLastTimestamp(pdx::Message& message) {
-  auto client = std::static_pointer_cast<VSyncChannel>(message.GetChannel());
-  std::lock_guard<std::mutex> autolock(mutex_);
-
-  // Getting the timestamp has the side effect of ACKing.
-  client->Ack();
-  return {current_vsync_};
-}
-
-pdx::Status<VSyncSchedInfo> VSyncService::OnGetSchedInfo(
-    pdx::Message& message) {
-  auto client = std::static_pointer_cast<VSyncChannel>(message.GetChannel());
-  std::lock_guard<std::mutex> autolock(mutex_);
-
-  // Getting the timestamp has the side effect of ACKing.
-  client->Ack();
-
-  uint32_t next_vsync_count = current_vsync_count_ + 1;
-  int64_t current_time = GetSystemClockNs();
-  int64_t vsync_period_ns = 0;
-  int64_t next_warp;
-  if (current_vsync_ == 0 || last_vsync_ == 0) {
-    // Handle startup when current_vsync_ or last_vsync_ are 0.
-    // Normally should not happen because vsync_service is running before
-    // applications, but in case it does a sane time prevents applications
-    // from malfunctioning.
-    vsync_period_ns = 20000000;
-    next_warp = current_time;
-  } else {
-    // TODO(jbates) When we have an accurate reading of the true vsync
-    // period, use that instead of this estimated value.
-    vsync_period_ns = current_vsync_ - last_vsync_;
-    // Clamp the period, because when there are no surfaces the last_vsync_
-    // value will get stale. Note this is temporary and goes away as soon
-    // as we have an accurate vsync period reported by the system.
-    vsync_period_ns = std::min(vsync_period_ns, INT64_C(20000000));
-    next_warp = current_vsync_ + vsync_period_ns - compositor_time_ns_;
-    // If the request missed the present window, move up to the next vsync.
-    if (current_time > next_warp) {
-      next_warp += vsync_period_ns;
-      ++next_vsync_count;
-    }
-  }
-
-  return {{vsync_period_ns, next_warp, next_vsync_count}};
-}
-
-pdx::Status<void> VSyncService::OnAcknowledge(pdx::Message& message) {
-  auto client = std::static_pointer_cast<VSyncChannel>(message.GetChannel());
-  std::lock_guard<std::mutex> autolock(mutex_);
-  client->Ack();
-  return {};
-}
-
-void VSyncWaiter::Notify(int64_t timestamp) {
-  timestamp_ = timestamp;
-  DispatchRemoteMethod<VSyncProtocol::Wait>(*this, &VSyncWaiter::OnWait,
-                                            message_);
-}
-
-pdx::Status<int64_t> VSyncWaiter::OnWait(pdx::Message& /*message*/) {
-  return {timestamp_};
-}
-
-void VSyncChannel::Ack() {
-  ALOGD_IF(TRACE > 1, "VSyncChannel::Ack: pid=%d cid=%d\n", pid_, cid_);
-  service_.ModifyChannelEvents(cid_, POLLPRI, 0);
-}
-
-void VSyncChannel::Signal() {
-  ALOGD_IF(TRACE > 1, "VSyncChannel::Signal: pid=%d cid=%d\n", pid_, cid_);
-  service_.ModifyChannelEvents(cid_, 0, POLLPRI);
-}
-
-}  // namespace dvr
-}  // namespace android
diff --git a/libs/vr/libvrflinger/vsync_service.h b/libs/vr/libvrflinger/vsync_service.h
deleted file mode 100644
index 822f02b..0000000
--- a/libs/vr/libvrflinger/vsync_service.h
+++ /dev/null
@@ -1,107 +0,0 @@
-#ifndef ANDROID_DVR_SERVICES_DISPLAYD_VSYNC_SERVICE_H_
-#define ANDROID_DVR_SERVICES_DISPLAYD_VSYNC_SERVICE_H_
-
-#include <pdx/service.h>
-
-#include <list>
-#include <memory>
-#include <mutex>
-#include <thread>
-
-#include "display_service.h"
-
-namespace android {
-namespace dvr {
-
-// VSyncWaiter encapsulates a client blocked waiting for the next vsync.
-// It is used to enqueue the Message to reply to when the next vsync event
-// occurs.
-class VSyncWaiter {
- public:
-  explicit VSyncWaiter(pdx::Message& message) : message_(std::move(message)) {}
-
-  void Notify(int64_t timestamp);
-
- private:
-  pdx::Status<int64_t> OnWait(pdx::Message& message);
-
-  pdx::Message message_;
-  int64_t timestamp_ = 0;
-
-  VSyncWaiter(const VSyncWaiter&) = delete;
-  void operator=(const VSyncWaiter&) = delete;
-};
-
-// VSyncChannel manages the service-side per-client context for each client
-// using the service.
-class VSyncChannel : public pdx::Channel {
- public:
-  VSyncChannel(pdx::Service& service, int pid, int cid)
-      : service_(service), pid_(pid), cid_(cid) {}
-
-  void Ack();
-  void Signal();
-
- private:
-  pdx::Service& service_;
-  pid_t pid_;
-  int cid_;
-
-  VSyncChannel(const VSyncChannel&) = delete;
-  void operator=(const VSyncChannel&) = delete;
-};
-
-// VSyncService implements the displayd vsync service over ServiceFS.
-class VSyncService : public pdx::ServiceBase<VSyncService> {
- public:
-  ~VSyncService() override;
-
-  pdx::Status<void> HandleMessage(pdx::Message& message) override;
-
-  std::shared_ptr<pdx::Channel> OnChannelOpen(pdx::Message& message) override;
-  void OnChannelClose(pdx::Message& message,
-                      const std::shared_ptr<pdx::Channel>& channel) override;
-
-  // Called by the hardware composer HAL, or similar, whenever a vsync event
-  // occurs on the primary display. |compositor_time_ns| is the number of ns
-  // before the next vsync when the compositor will preempt the GPU to do EDS
-  // and lens warp.
-  void VSyncEvent(int64_t timestamp_ns, int64_t compositor_time_ns,
-                  uint32_t vsync_count);
-
- private:
-  friend BASE;
-
-  VSyncService();
-
-  pdx::Status<int64_t> OnGetLastTimestamp(pdx::Message& message);
-  pdx::Status<display::VSyncSchedInfo> OnGetSchedInfo(pdx::Message& message);
-  pdx::Status<void> OnAcknowledge(pdx::Message& message);
-
-  void NotifierThreadFunction();
-
-  void AddWaiter(pdx::Message& message);
-  void NotifyWaiters();
-  void UpdateClients();
-
-  void AddClient(const std::shared_ptr<VSyncChannel>& client);
-  void RemoveClient(const std::shared_ptr<VSyncChannel>& client);
-
-  int64_t last_vsync_;
-  int64_t current_vsync_;
-  int64_t compositor_time_ns_;
-  uint32_t current_vsync_count_;
-
-  std::mutex mutex_;
-
-  std::list<std::unique_ptr<VSyncWaiter>> waiters_;
-  std::list<std::shared_ptr<VSyncChannel>> clients_;
-
-  VSyncService(const VSyncService&) = delete;
-  void operator=(VSyncService&) = delete;
-};
-
-}  // namespace dvr
-}  // namespace android
-
-#endif  // ANDROID_DVR_SERVICES_DISPLAYD_VSYNC_SERVICE_H_
diff --git a/services/surfaceflinger/DispSync.cpp b/services/surfaceflinger/DispSync.cpp
index eb271cd..829b53d 100644
--- a/services/surfaceflinger/DispSync.cpp
+++ b/services/surfaceflinger/DispSync.cpp
@@ -236,14 +236,6 @@
         return BAD_VALUE;
     }
 
-    // This method is only here to handle the !SurfaceFlinger::hasSyncFramework
-    // case.
-    bool hasAnyEventListeners() {
-        if (kTraceDetailedInfo) ATRACE_CALL();
-        Mutex::Autolock lock(mMutex);
-        return !mEventListeners.empty();
-    }
-
 private:
     struct EventListener {
         const char* mName;
@@ -407,22 +399,18 @@
     reset();
     beginResync();
 
-    if (kTraceDetailedInfo) {
-        // If we're not getting present fences then the ZeroPhaseTracer
-        // would prevent HW vsync event from ever being turned off.
-        // Even if we're just ignoring the fences, the zero-phase tracing is
-        // not needed because any time there is an event registered we will
-        // turn on the HW vsync events.
-        if (!mIgnorePresentFences && kEnableZeroPhaseTracer) {
-            mZeroPhaseTracer = std::make_unique<ZeroPhaseTracer>();
-            addEventListener("ZeroPhaseTracer", 0, mZeroPhaseTracer.get());
-        }
+    if (kTraceDetailedInfo && kEnableZeroPhaseTracer) {
+        mZeroPhaseTracer = std::make_unique<ZeroPhaseTracer>();
+        addEventListener("ZeroPhaseTracer", 0, mZeroPhaseTracer.get());
     }
 }
 
 void DispSync::reset() {
     Mutex::Autolock lock(mMutex);
+    resetLocked();
+}
 
+void DispSync::resetLocked() {
     mPhase = 0;
     mReferenceTime = 0;
     mModelUpdated = false;
@@ -435,6 +423,10 @@
 bool DispSync::addPresentFence(const std::shared_ptr<FenceTime>& fenceTime) {
     Mutex::Autolock lock(mMutex);
 
+    if (mIgnorePresentFences) {
+        return true;
+    }
+
     mPresentFences[mPresentSampleOffset] = fenceTime;
     mPresentSampleOffset = (mPresentSampleOffset + 1) % NUM_PRESENT_SAMPLES;
     mNumResyncSamplesSincePresent = 0;
@@ -480,12 +472,10 @@
     }
 
     if (mIgnorePresentFences) {
-        // If we don't have the sync framework we will never have
-        // addPresentFence called.  This means we have no way to know whether
+        // If we're ignoring the present fences we have no way to know whether
         // or not we're synchronized with the HW vsyncs, so we just request
-        // that the HW vsync events be turned on whenever we need to generate
-        // SW vsync events.
-        return mThread->hasAnyEventListeners();
+        // that the HW vsync events be turned on.
+        return true;
     }
 
     // Check against kErrorThreshold / 2 to add some hysteresis before having to
@@ -659,6 +649,14 @@
     return (((now - phase) / mPeriod) + periodOffset + 1) * mPeriod + phase;
 }
 
+void DispSync::setIgnorePresentFences(bool ignore) {
+    Mutex::Autolock lock(mMutex);
+    if (mIgnorePresentFences != ignore) {
+        mIgnorePresentFences = ignore;
+        resetLocked();
+    }
+}
+
 void DispSync::dump(String8& result) const {
     Mutex::Autolock lock(mMutex);
     result.appendFormat("present fences are %s\n", mIgnorePresentFences ? "ignored" : "used");
diff --git a/services/surfaceflinger/DispSync.h b/services/surfaceflinger/DispSync.h
index 077256a..c00c161 100644
--- a/services/surfaceflinger/DispSync.h
+++ b/services/surfaceflinger/DispSync.h
@@ -124,12 +124,21 @@
     // the refresh after next. etc.
     nsecs_t computeNextRefresh(int periodOffset) const;
 
+    // In certain situations the present fences aren't a good indicator of vsync
+    // time, e.g. when vr flinger is active, or simply aren't available,
+    // e.g. when the sync framework isn't present. Use this method to toggle
+    // whether or not DispSync ignores present fences. If present fences are
+    // ignored, DispSync will always ask for hardware vsync events by returning
+    // true from addPresentFence() and addResyncSample().
+    void setIgnorePresentFences(bool ignore);
+
     // dump appends human-readable debug info to the result string.
     void dump(String8& result) const;
 
 private:
     void updateModelLocked();
     void updateErrorLocked();
+    void resetLocked();
     void resetErrorLocked();
 
     enum { MAX_RESYNC_SAMPLES = 32 };
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 2d6d470..96d1c76 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1355,6 +1355,8 @@
 
 void SurfaceFlinger::onVsyncReceived(int32_t sequenceId, hwc2_display_t hwcDisplayId,
                                      int64_t timestamp) {
+    ATRACE_NAME("SF onVsync");
+
     Mutex::Autolock lock(mStateLock);
     // Ignore any vsyncs from a previous hardware composer.
     if (sequenceId != getBE().mComposerSequenceId) {
@@ -1366,11 +1368,16 @@
         return;
     }
 
+    if (type != DisplayDevice::DISPLAY_PRIMARY) {
+        // For now, we don't do anything with external display vsyncs.
+        return;
+    }
+
     bool needsHwVsync = false;
 
     { // Scope for the lock
         Mutex::Autolock _l(mHWVsyncLock);
-        if (type == DisplayDevice::DISPLAY_PRIMARY && mPrimaryHWVsyncEnabled) {
+        if (mPrimaryHWVsyncEnabled) {
             needsHwVsync = mPrimaryDispSync.addResyncSample(timestamp);
         }
     }
@@ -1481,8 +1488,6 @@
 
     if (vrFlingerRequestsDisplay) {
         mVrFlinger->GrantDisplayOwnership();
-    } else {
-        enableHardwareVsync();
     }
 
     mVisibleRegionsDirty = true;
@@ -1498,10 +1503,17 @@
     const nsecs_t period = activeConfig->getVsyncPeriod();
     mAnimFrameTracker.setDisplayRefreshPeriod(period);
 
+    // The present fences returned from vr_hwc are not an accurate
+    // representation of vsync times.
+    mPrimaryDispSync.setIgnorePresentFences(
+            getBE().mHwc->isUsingVrComposer() || !hasSyncFramework);
+
     // Use phase of 0 since phase is not known.
     // Use latency of 0, which will snap to the ideal latency.
     setCompositorTimingSnapped(0, period, 0);
 
+    resyncToHardwareVsync(false);
+
     android_atomic_or(1, &mRepaintEverything);
     setTransactionFlags(eDisplayTransactionNeeded);
 }
diff --git a/services/vr/hardware_composer/Android.bp b/services/vr/hardware_composer/Android.bp
index 0c91b07..003775b 100644
--- a/services/vr/hardware_composer/Android.bp
+++ b/services/vr/hardware_composer/Android.bp
@@ -39,6 +39,10 @@
     "android.hardware.graphics.composer@2.1-hal",
   ],
 
+  export_static_lib_headers: [
+    "libdisplay",
+  ],
+
   export_shared_lib_headers: [
     "android.frameworks.vr.composer@1.0",
     "android.hardware.graphics.composer@2.1",
@@ -48,6 +52,7 @@
 
   cflags: [
     "-DLOG_TAG=\"vr_hwc\"",
+    "-DATRACE_TAG=ATRACE_TAG_GRAPHICS",
     "-Wall",
     "-Werror",
     // mVrClient unused in vr_composer_client.cpp
diff --git a/services/vr/hardware_composer/impl/vr_hwc.cpp b/services/vr/hardware_composer/impl/vr_hwc.cpp
index 4af47d2..d1ed12b 100644
--- a/services/vr/hardware_composer/impl/vr_hwc.cpp
+++ b/services/vr/hardware_composer/impl/vr_hwc.cpp
@@ -16,9 +16,11 @@
 #include "impl/vr_hwc.h"
 
 #include "android-base/stringprintf.h"
+#include <binder/IServiceManager.h>
 #include <cutils/properties.h>
 #include <private/dvr/display_client.h>
 #include <ui/Fence.h>
+#include <utils/Trace.h>
 
 #include <mutex>
 
@@ -244,29 +246,38 @@
 ////////////////////////////////////////////////////////////////////////////////
 // VrHwcClient
 
-VrHwc::VrHwc() {}
+VrHwc::VrHwc() {
+  vsync_callback_ = new VsyncCallback;
+}
 
-VrHwc::~VrHwc() {}
+VrHwc::~VrHwc() {
+  vsync_callback_->SetEventCallback(nullptr);
+}
 
 bool VrHwc::hasCapability(hwc2_capability_t /* capability */) { return false; }
 
 void VrHwc::registerEventCallback(EventCallback* callback) {
-  {
-    std::lock_guard<std::mutex> guard(mutex_);
-    event_callback_ = callback;
-    int32_t width, height;
-    GetPrimaryDisplaySize(&width, &height);
-    // Create the primary display late to avoid initialization issues between
-    // VR HWC and SurfaceFlinger.
-    displays_[kDefaultDisplayId].reset(new HwcDisplay(width, height));
-  }
+  std::unique_lock<std::mutex> lock(mutex_);
+  event_callback_ = callback;
+  int32_t width, height;
+  GetPrimaryDisplaySize(&width, &height);
+  // Create the primary display late to avoid initialization issues between
+  // VR HWC and SurfaceFlinger.
+  displays_[kDefaultDisplayId].reset(new HwcDisplay(width, height));
+
+  // Surface flinger will make calls back into vr_hwc when it receives the
+  // onHotplug() call, so it's important to release mutex_ here.
+  lock.unlock();
   event_callback_->onHotplug(kDefaultDisplayId,
                              IComposerCallback::Connection::CONNECTED);
+  lock.lock();
+  UpdateVsyncCallbackEnabledLocked();
 }
 
 void VrHwc::unregisterEventCallback() {
   std::lock_guard<std::mutex> guard(mutex_);
   event_callback_ = nullptr;
+  UpdateVsyncCallbackEnabledLocked();
 }
 
 uint32_t VrHwc::getMaxVirtualDisplayCount() { return 1; }
@@ -475,8 +486,45 @@
   if (!display_ptr)
     return Error::BAD_DISPLAY;
 
-  display_ptr->set_vsync_enabled(enabled);
-  return Error::NONE;
+  if (enabled != IComposerClient::Vsync::ENABLE &&
+      enabled != IComposerClient::Vsync::DISABLE) {
+    return Error::BAD_PARAMETER;
+  }
+
+  Error set_vsync_result = Error::NONE;
+  if (display == kDefaultDisplayId) {
+    sp<IVsyncService> vsync_service = interface_cast<IVsyncService>(
+        defaultServiceManager()->getService(
+            String16(IVsyncService::GetServiceName())));
+    if (vsync_service == nullptr) {
+      ALOGE("Failed to get vsync service");
+      return Error::NO_RESOURCES;
+    }
+
+    if (enabled == IComposerClient::Vsync::ENABLE) {
+      ALOGI("Enable vsync");
+      display_ptr->set_vsync_enabled(true);
+      status_t result = vsync_service->registerCallback(vsync_callback_);
+      if (result != OK) {
+        ALOGE("%s service registerCallback() failed: %s (%d)",
+            IVsyncService::GetServiceName(), strerror(-result), result);
+        set_vsync_result = Error::NO_RESOURCES;
+      }
+    } else if (enabled == IComposerClient::Vsync::DISABLE) {
+      ALOGI("Disable vsync");
+      display_ptr->set_vsync_enabled(false);
+      status_t result = vsync_service->unregisterCallback(vsync_callback_);
+      if (result != OK) {
+        ALOGE("%s service unregisterCallback() failed: %s (%d)",
+            IVsyncService::GetServiceName(), strerror(-result), result);
+        set_vsync_result = Error::NO_RESOURCES;
+      }
+    }
+
+    UpdateVsyncCallbackEnabledLocked();
+  }
+
+  return set_vsync_result;
 }
 
 Error VrHwc::setColorTransform(Display display, const float* matrix,
@@ -559,7 +607,8 @@
   frame.display_height = display_ptr->height();
   frame.active_config = display_ptr->active_config();
   frame.power_mode = display_ptr->power_mode();
-  frame.vsync_enabled = display_ptr->vsync_enabled();
+  frame.vsync_enabled = display_ptr->vsync_enabled() ?
+      IComposerClient::Vsync::ENABLE : IComposerClient::Vsync::DISABLE;
   frame.color_transform_hint = display_ptr->color_transform_hint();
   frame.color_mode = display_ptr->color_mode();
   memcpy(frame.color_transform, display_ptr->color_transform(),
@@ -911,6 +960,15 @@
   return iter == displays_.end() ? nullptr : iter->second.get();
 }
 
+void VrHwc::UpdateVsyncCallbackEnabledLocked() {
+  auto primary_display = FindDisplay(kDefaultDisplayId);
+  LOG_ALWAYS_FATAL_IF(event_callback_ != nullptr && primary_display == nullptr,
+      "Should have created the primary display by now");
+  bool send_vsync =
+      event_callback_ != nullptr && primary_display->vsync_enabled();
+  vsync_callback_->SetEventCallback(send_vsync ? event_callback_ : nullptr);
+}
+
 void HwcLayer::dumpDebugInfo(std::string* result) const {
   if (!result) {
     return;
@@ -928,5 +986,18 @@
       buffer_metadata.layerCount, buffer_metadata.format);
 }
 
+status_t VrHwc::VsyncCallback::onVsync(int64_t vsync_timestamp) {
+  ATRACE_NAME("vr_hwc onVsync");
+  std::lock_guard<std::mutex> guard(mutex_);
+  if (callback_ != nullptr)
+    callback_->onVsync(kDefaultDisplayId, vsync_timestamp);
+  return NO_ERROR;
+}
+
+void VrHwc::VsyncCallback::SetEventCallback(EventCallback* callback) {
+  std::lock_guard<std::mutex> guard(mutex_);
+  callback_ = callback;
+}
+
 }  // namespace dvr
 }  // namespace android
diff --git a/services/vr/hardware_composer/impl/vr_hwc.h b/services/vr/hardware_composer/impl/vr_hwc.h
index 85e587a..f9872b2 100644
--- a/services/vr/hardware_composer/impl/vr_hwc.h
+++ b/services/vr/hardware_composer/impl/vr_hwc.h
@@ -20,6 +20,7 @@
 #include <android/frameworks/vr/composer/1.0/IVrComposerClient.h>
 #include <android/hardware/graphics/composer/2.1/IComposer.h>
 #include <composer-hal/2.1/ComposerHal.h>
+#include <private/dvr/vsync_service.h>
 #include <ui/Fence.h>
 #include <ui/GraphicBuffer.h>
 #include <utils/StrongPointer.h>
@@ -156,10 +157,8 @@
   IComposerClient::PowerMode power_mode() const { return power_mode_; }
   void set_power_mode(IComposerClient::PowerMode mode) { power_mode_ = mode; }
 
-  IComposerClient::Vsync vsync_enabled() const { return vsync_enabled_; }
-  void set_vsync_enabled(IComposerClient::Vsync vsync) {
-    vsync_enabled_ = vsync;
-  }
+  bool vsync_enabled() const { return vsync_enabled_; }
+  void set_vsync_enabled(bool vsync) {vsync_enabled_ = vsync;}
 
   const float* color_transform() const { return color_transform_; }
   int32_t color_transform_hint() const { return color_transform_hint_; }
@@ -187,7 +186,7 @@
   Config active_config_;
   ColorMode color_mode_;
   IComposerClient::PowerMode power_mode_;
-  IComposerClient::Vsync vsync_enabled_;
+  bool vsync_enabled_ = false;
   float color_transform_[16];
   int32_t color_transform_hint_;
 
@@ -299,8 +298,23 @@
   void UnregisterObserver(Observer* observer) override;
 
  private:
+  class VsyncCallback : public BnVsyncCallback {
+   public:
+    status_t onVsync(int64_t vsync_timestamp) override;
+    void SetEventCallback(EventCallback* callback);
+   private:
+    std::mutex mutex_;
+    EventCallback* callback_;
+  };
+
   HwcDisplay* FindDisplay(Display display);
 
+  // Re-evaluate whether or not we should start making onVsync() callbacks to
+  // the client. We need enableCallback(true) to have been called, and
+  // setVsyncEnabled() to have been called for the primary display. The caller
+  // must have mutex_ locked already.
+  void UpdateVsyncCallbackEnabledLocked();
+
   wp<VrComposerClient> client_;
 
   // Guard access to internal state from binder threads.
@@ -312,6 +326,8 @@
   EventCallback* event_callback_ = nullptr;
   Observer* observer_ = nullptr;
 
+  sp<VsyncCallback> vsync_callback_;
+
   VrHwc(const VrHwc&) = delete;
   void operator=(const VrHwc&) = delete;
 };