[Ozone-DRI] Reuse framebuffer when re-enabling CRTC

ui/ozone/platform/dri/hardware_display_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/ozone/platform/dri/hardware_display_controller.h"
 
 #include <drm.h>
 #include <errno.h>
 #include <string.h>
 #include <xf86drm.h>
@@ skipping 30 matching lines @@
                          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_));
   AddCrtc(controller.Pass());
 }
 
 HardwareDisplayController::~HardwareDisplayController() {
   // Reset the cursor.
   UnsetCursor();
 }
 
 bool HardwareDisplayController::Modeset(const OverlayPlane& primary,
                                         drmModeModeInfo mode) {
   TRACE_EVENT0("dri", "HDC::Modeset");
   DCHECK(primary.buffer.get());
   bool status = true;
   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;
   return status;
 }
 
 bool HardwareDisplayController::Enable() {
   TRACE_EVENT0("dri", "HDC::Enable");
   DCHECK(!current_planes_.empty());
   const OverlayPlane* primary = OverlayPlane::GetPrimaryPlane(current_planes_);
-  DCHECK(primary->buffer.get());
-  bool status = true;
-  for (size_t i = 0; i < crtc_controllers_.size(); ++i)
-    status &= crtc_controllers_[i]->Modeset(*primary, mode_);
 
-  return status;
+  return Modeset(*primary, mode_);
 }
 
 void HardwareDisplayController::Disable() {
   TRACE_EVENT0("dri", "HDC::Disable");
   for (size_t i = 0; i < crtc_controllers_.size(); ++i)
     crtc_controllers_[i]->Disable();
 
   is_disabled_ = true;
 }
 
@@ skipping 144 matching lines @@
 uint64_t HardwareDisplayController::GetTimeOfLastFlip() const {
   uint64_t time = 0;
   for (size_t i = 0; i < crtc_controllers_.size(); ++i)
     if (time < crtc_controllers_[i]->time_of_last_flip())
       time = crtc_controllers_[i]->time_of_last_flip();
 
   return time;
 }
 
 }  // namespace ui