[Ozone-DRI] Listen for swap events

ui/ozone/platform/dri/hardware_display_controller.cc

Index: ui/ozone/platform/dri/hardware_display_controller.cc
diff --git a/ui/ozone/platform/dri/hardware_display_controller.cc b/ui/ozone/platform/dri/hardware_display_controller.cc
index 7ec4f0dcbc95c4e1f5cc0b4e7883a3fffd9b2db1..7f81355ac93eb4ba436e05cb961114d26bb6286a 100644
--- a/ui/ozone/platform/dri/hardware_display_controller.cc
+++ b/ui/ozone/platform/dri/hardware_display_controller.cc
@@ -22,39 +22,19 @@
 
 namespace ui {
 
-namespace {
-
-// DRM callback on page flip events. This callback is triggered after the
-// page flip has happened and the backbuffer is now the new frontbuffer
-// The old frontbuffer is no longer used by the hardware and can be used for
-// future draw operations.
-//
-// |device| will contain a reference to the |ScanoutSurface| object which
-// the event belongs to.
-//
-// TODO(dnicoara) When we have a FD handler for the DRM calls in the message
-// loop, we can move this function in the handler.
-void HandlePageFlipEvent(int fd,
-                         unsigned int frame,
-                         unsigned int seconds,
-                         unsigned int useconds,
-                         void* controller) {
-  static_cast<CrtcController*>(controller)
-      ->OnPageFlipEvent(frame, seconds, useconds);
-}
-
-}  // namespace
-
 HardwareDisplayController::HardwareDisplayController(
     scoped_ptr<CrtcController> controller)
     : is_disabled_(true) {
   memset(&mode_, 0, sizeof(mode_));
+  pending_planes_.push_back(OverlayPlaneList());
   AddCrtc(controller.Pass());
 }
 
 HardwareDisplayController::~HardwareDisplayController() {
   // Reset the cursor.
   UnsetCursor();
+  if (!page_flip_callback_.is_null())
+    page_flip_callback_.Run();
 }
 
 bool HardwareDisplayController::Modeset(const OverlayPlane& primary,
@@ -65,10 +45,25 @@ bool HardwareDisplayController::Modeset(const OverlayPlane& primary,
   for (size_t i = 0; i < crtc_controllers_.size(); ++i)
     status &= crtc_controllers_[i]->Modeset(primary, mode);
 
-  current_planes_ = std::vector<OverlayPlane>(1, primary);
-  pending_planes_.clear();
   is_disabled_ = false;
   mode_ = mode;
+
+  current_planes_ = std::vector<OverlayPlane>(1, primary);
+  pending_planes_.clear();
+
+  while (!callbacks_.empty()) {
+    callbacks_.front().Run();
+    callbacks_.pop_front();
+  }
+
+  // Because a page flip is pending we need to leave some state for the
+  // callback. We use the modeset state since it is the only valid state.
+  if (HasPendingPageFlips())
+    pending_planes_.push_back(current_planes_);
+
+  // Need to insert an empty list to accomodate future requests.
+  pending_planes_.push_back(OverlayPlaneList());
+
   return status;
 }
 
@@ -89,64 +84,28 @@ void HardwareDisplayController::Disable() {
 }
 
 void HardwareDisplayController::QueueOverlayPlane(const OverlayPlane& plane) {
-  pending_planes_.push_back(plane);
+  pending_planes_.back().push_back(plane);
 }
 
-bool HardwareDisplayController::SchedulePageFlip() {
-  DCHECK(!pending_planes_.empty());
+bool HardwareDisplayController::SchedulePageFlip(
+    const base::Closure& callback) {
+  TRACE_EVENT1("dri", "HDC::SchedulePageFlip", "this", this);
 
-  if (is_disabled_)
+  if (pending_planes_.size() > 1) {
+    callbacks_.push_back(callback);
     return true;
-
-  std::sort(pending_planes_.begin(), pending_planes_.end(),
-            [](const OverlayPlane& l, const OverlayPlane& r) {
-    return l.z_order < r.z_order;
-  });
-
-  bool status = true;
-  for (size_t i = 0; i < crtc_controllers_.size(); ++i) {
-    status &= crtc_controllers_[i]->SchedulePageFlip(
-        owned_hardware_planes_.get(crtc_controllers_[i]->drm()),
-        pending_planes_);
   }
 
-  for (const auto& planes : owned_hardware_planes_) {
-    if (!planes.first->plane_manager()->Commit(planes.second)) {
-      status = false;
-    }
+  bool status =
+      ActualSchedulePageFlip(pending_planes_.front(), callbacks_.front());
+  if (!status) {
+    pending_planes_.pop_front();
+    callbacks_.pop_front();
   }
 
   return status;
 }
 
-void HardwareDisplayController::WaitForPageFlipEvent() {
-  TRACE_EVENT0("dri", "HDC::WaitForPageFlipEvent");
-
-  drmEventContext drm_event;
-  drm_event.version = DRM_EVENT_CONTEXT_VERSION;
-  drm_event.page_flip_handler = HandlePageFlipEvent;
-  drm_event.vblank_handler = NULL;
-
-  bool has_pending_page_flips = false;
-  // Wait for the page-flips to complete.
-  for (size_t i = 0; i < crtc_controllers_.size(); ++i) {
-    // In mirror mode the page flip callbacks can happen in different order than
-    // scheduled, so we need to make sure that the event for the current CRTC is
-    // processed before moving to the next CRTC.
-    while (crtc_controllers_[i]->page_flip_pending()) {
-      has_pending_page_flips = true;
-      crtc_controllers_[i]->drm()->HandleEvent(drm_event);
-    }
-  }
-
-  // In case there are no pending pageflips do not replace the current planes
-  // since they are still being used.
-  if (has_pending_page_flips)
-    current_planes_.swap(pending_planes_);
-
-  pending_planes_.clear();
-}
-
 bool HardwareDisplayController::SetCursor(
     const scoped_refptr<ScanoutBuffer>& buffer) {
   bool status = true;
@@ -183,6 +142,7 @@ void HardwareDisplayController::AddCrtc(scoped_ptr<CrtcController> controller) {
   owned_hardware_planes_.add(
       controller->drm(),
       scoped_ptr<HardwareDisplayPlaneList>(new HardwareDisplayPlaneList()));
+  controller->AddObserver(this);
   crtc_controllers_.push_back(controller.release());
 }
 
@@ -192,6 +152,7 @@ scoped_ptr<CrtcController> HardwareDisplayController::RemoveCrtc(
        it != crtc_controllers_.end(); ++it) {
     if ((*it)->crtc() == crtc) {
       scoped_ptr<CrtcController> controller(*it);
+      controller->RemoveObserver(this);
       crtc_controllers_.weak_erase(it);
       // Remove entry from |owned_hardware_planes_| iff no other crtcs share it.
       bool found = false;
@@ -205,6 +166,11 @@ scoped_ptr<CrtcController> HardwareDisplayController::RemoveCrtc(
       }
       if (!found)
         owned_hardware_planes_.erase(controller->drm());
+
+      // If a display configuration happens mid page flip we want to make sure
+      // the HDC won't wait for an event from a CRTC that is no longer
+      // associated with it.
+      OnPageFlipEvent();
       return controller.Pass();
     }
   }
@@ -241,4 +207,85 @@ uint64_t HardwareDisplayController::GetTimeOfLastFlip() const {
   return time;
 }
 
+void HardwareDisplayController::OnPageFlipEvent() {
+  TRACE_EVENT1("dri", "HDC::OnPageFlipEvent", "this", this);
+  if (page_flip_callback_.is_null())
+    return;
+
+  if (HasPendingPageFlips())
+    return;
+
+  current_planes_.swap(pending_planes_.front());
+  pending_planes_.pop_front();
+
+  // Modesetting can clear the callbacks.
+  if (!callbacks_.empty()) {
+    base::Closure callback = callbacks_.front();
+    callbacks_.pop_front();
+    callback.Run();
+  }
+
+  // If we have pending requests immediately start the next one.
+  if (!pending_planes_.empty() && !pending_planes_.front().empty() &&
+      !callbacks_.empty()) {
+    base::Closure callback = callbacks_.front();
+    bool status = ActualSchedulePageFlip(pending_planes_.front(), callback);
+    if (!status) {
+      pending_planes_.pop_front();
+      callbacks_.pop_front();
+
+      // Normally the caller would handle the error call, but because we're in a
+      // delayed schedule the initial SchedulePageFlip() already returned true,
+      // this we need to run the callback.
+      callback.Run();
+    }
+  }
+}
+
+bool HardwareDisplayController::HasPendingPageFlips() const {
+  for (size_t i = 0; i < crtc_controllers_.size(); ++i)
+    if (crtc_controllers_[i]->page_flip_pending())
+      return true;
+
+  return false;
+}
+
+bool HardwareDisplayController::ActualSchedulePageFlip(
+    OverlayPlaneList pending_planes,
+    const base::Closure& callback) {
+  TRACE_EVENT0("dri", "HDC::ActualSchedulePageFlip");
+  if (is_disabled_) {
+    callback.Run();
+    return true;
+  }
+
+  // Any overlays in the last list will be scheduled together. Insert an empty
+  // list for the next request.
+  if (!pending_planes_.back().empty())
+    pending_planes_.push_back(OverlayPlaneList());
+
+  std::sort(pending_planes.begin(), pending_planes.end(),
+            [](const OverlayPlane& l, const OverlayPlane& r) {
+    return l.z_order < r.z_order;
+  });
+
+  bool status = true;
+  for (size_t i = 0; i < crtc_controllers_.size(); ++i) {
+    status &= crtc_controllers_[i]->SchedulePageFlip(
+        owned_hardware_planes_.get(crtc_controllers_[i]->drm()),
+        pending_planes);
+  }
+
+  for (const auto& planes : owned_hardware_planes_) {
+    if (!planes.first->plane_manager()->Commit(planes.second)) {
+      status = false;
+    }
+  }
+
+  if (!status)
+    callback.Run();
+
+  return status;
+}
+
 }  // namespace ui