sdm: Merge release fence after set power mode

On SetPowerMode() with retain pipes, DRM driver triggers the kick off
that enables MDP to read the previously queued buffer, Since the fence
created during SetPowerMode() is not merged with the previously queued
buffer, it may result in tearing. Hence get the release fence from
driver on SetPowerMode and propagate it to hwcomposer to merge it with
the previous release fence of all layer buffers to avoid tearing.

Change-Id: I81c078a1b05dd3fb34f10b9b70e25cfbcfabd117
CRs-Fixed: 2184515

sdm/include/core/display_interface.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -388,12 +388,13 @@ class DisplayInterface {
   /*! @brief Method to set current state of the display device.
 
     @param[in] state \link DisplayState \endlink
+    @param[in] pointer to release fence
 
     @return \link DisplayError \endlink
 
     @sa SetDisplayState
   */
-  virtual DisplayError SetDisplayState(DisplayState state) = 0;
+  virtual DisplayError SetDisplayState(DisplayState state, int *release_fence) = 0;
 
   /*! @brief Method to set active configuration for variable properties of the display device.
 

sdm/libs/core/display_base.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -430,7 +430,7 @@ DisplayState DisplayBase::GetLastPowerMode() {
   return last_power_mode_;
 }
 
-DisplayError DisplayBase::SetDisplayState(DisplayState state) {
+DisplayError DisplayBase::SetDisplayState(DisplayState state, int *release_fence) {
   lock_guard<recursive_mutex> obj(recursive_mutex_);
   DisplayError error = kErrorNone;
   bool active = false;
@@ -452,7 +452,7 @@ DisplayError DisplayBase::SetDisplayState(DisplayState state) {
     break;
 
   case kStateOn:
-    error = hw_intf_->PowerOn();
+    error = hw_intf_->PowerOn(release_fence);
     if (error != kErrorNone) {
       return error;
     }
@@ -468,13 +468,13 @@ DisplayError DisplayBase::SetDisplayState(DisplayState state) {
     break;
 
   case kStateDoze:
-    error = hw_intf_->Doze();
+    error = hw_intf_->Doze(release_fence);
     active = true;
     last_power_mode_ = kStateDoze;
     break;
 
   case kStateDozeSuspend:
-    error = hw_intf_->DozeSuspend();
+    error = hw_intf_->DozeSuspend(release_fence);
     if (display_type_ != kPrimary) {
       active = true;
     }

sdm/libs/core/display_base.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -62,7 +62,7 @@ class DisplayBase : public DisplayInterface {
   virtual DisplayError GetConfig(DisplayConfigFixedInfo *variable_info);
   virtual DisplayError GetActiveConfig(uint32_t *index);
   virtual DisplayError GetVSyncState(bool *enabled);
-  virtual DisplayError SetDisplayState(DisplayState state);
+  virtual DisplayError SetDisplayState(DisplayState state, int *release_fence);
   virtual DisplayError SetActiveConfig(uint32_t index);
   virtual DisplayError SetActiveConfig(DisplayConfigVariableInfo *variable_info) {
     return kErrorNotSupported;

sdm/libs/core/display_primary.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -166,10 +166,10 @@ DisplayError DisplayPrimary::Commit(LayerStack *layer_stack) {
   return error;
 }
 
-DisplayError DisplayPrimary::SetDisplayState(DisplayState state) {
+DisplayError DisplayPrimary::SetDisplayState(DisplayState state, int *release_fence) {
   lock_guard<recursive_mutex> obj(recursive_mutex_);
   DisplayError error = kErrorNone;
-  error = DisplayBase::SetDisplayState(state);
+  error = DisplayBase::SetDisplayState(state, release_fence);
   if (error != kErrorNone) {
     return error;
   }
@@ -391,19 +391,26 @@ bool DisplayPrimary::NeedsAVREnable() {
 
 void DisplayPrimary::ResetPanel() {
   DisplayError status = kErrorNone;
+  int release_fence = -1;
 
   DLOGI("Powering off primary");
-  status = SetDisplayState(kStateOff);
+  status = SetDisplayState(kStateOff, &release_fence);
   if (status != kErrorNone) {
     DLOGE("power-off on primary failed with error = %d", status);
   }
+  if (release_fence >= 0) {
+    ::close(release_fence);
+  }
 
   DLOGI("Restoring power mode on primary");
   DisplayState mode = GetLastPowerMode();
-  status = SetDisplayState(mode);
+  status = SetDisplayState(mode, &release_fence);
   if (status != kErrorNone) {
     DLOGE("Setting power mode = %d on primary failed with error = %d", mode, status);
   }
+  if (release_fence >= 0) {
+    ::close(release_fence);
+  }
 
   DLOGI("Enabling HWVsync");
   status = SetVSyncState(true);

sdm/libs/core/display_primary.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -44,7 +44,7 @@ class DisplayPrimary : public DisplayBase, HWEventHandler {
   virtual DisplayError Commit(LayerStack *layer_stack);
   virtual DisplayError ControlPartialUpdate(bool enable, uint32_t *pending);
   virtual DisplayError DisablePartialUpdateOneFrame();
-  virtual DisplayError SetDisplayState(DisplayState state);
+  virtual DisplayError SetDisplayState(DisplayState state, int *release_fence);
   virtual void SetIdleTimeoutMs(uint32_t active_ms);
   virtual DisplayError SetDisplayMode(uint32_t mode);
   virtual DisplayError GetRefreshRateRange(uint32_t *min_refresh_rate, uint32_t *max_refresh_rate);

sdm/libs/core/drm/hw_device_drm.cpp

@@ -709,7 +709,7 @@ DisplayError HWDeviceDRM::GetConfigIndex(char *mode, uint32_t *index) {
   return kErrorNone;
 }
 
-DisplayError HWDeviceDRM::PowerOn() {
+DisplayError HWDeviceDRM::PowerOn(int *release_fence) {
   DTRACE_SCOPED();
   if (!drm_atomic_intf_) {
     DLOGE("DRM Atomic Interface is null!");
@@ -727,6 +727,7 @@ DisplayError HWDeviceDRM::PowerOn() {
     DLOGE("Failed with error: %d", ret);
     return kErrorHardware;
   }
+  drm_atomic_intf_->Perform(DRMOps::CRTC_GET_RELEASE_FENCE, token_.crtc_id, release_fence);
 
   return kErrorNone;
 }
@@ -750,7 +751,7 @@ DisplayError HWDeviceDRM::PowerOff() {
   return kErrorNone;
 }
 
-DisplayError HWDeviceDRM::Doze() {
+DisplayError HWDeviceDRM::Doze(int *release_fence) {
   DTRACE_SCOPED();
   drm_atomic_intf_->Perform(DRMOps::CRTC_SET_ACTIVE, token_.crtc_id, 1);
   drm_atomic_intf_->Perform(DRMOps::CONNECTOR_SET_POWER_MODE, token_.conn_id, DRMPowerMode::DOZE);
@@ -760,10 +761,12 @@ DisplayError HWDeviceDRM::Doze() {
     return kErrorHardware;
   }
 
+  drm_atomic_intf_->Perform(DRMOps::CRTC_GET_RELEASE_FENCE, token_.crtc_id, release_fence);
+
   return kErrorNone;
 }
 
-DisplayError HWDeviceDRM::DozeSuspend() {
+DisplayError HWDeviceDRM::DozeSuspend(int *release_fence) {
   DTRACE_SCOPED();
   drm_atomic_intf_->Perform(DRMOps::CRTC_SET_ACTIVE, token_.crtc_id, 1);
   drm_atomic_intf_->Perform(DRMOps::CONNECTOR_SET_POWER_MODE, token_.conn_id,
@@ -774,6 +777,8 @@ DisplayError HWDeviceDRM::DozeSuspend() {
     return kErrorHardware;
   }
 
+  drm_atomic_intf_->Perform(DRMOps::CRTC_GET_RELEASE_FENCE, token_.crtc_id, release_fence);
+
   return kErrorNone;
 }
 

sdm/libs/core/drm/hw_device_drm.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -67,10 +67,10 @@ class HWDeviceDRM : public HWInterface {
   virtual DisplayError SetDisplayAttributes(uint32_t index);
   virtual DisplayError SetDisplayAttributes(const HWDisplayAttributes &display_attributes);
   virtual DisplayError GetConfigIndex(char *mode, uint32_t *index);
-  virtual DisplayError PowerOn();
+  virtual DisplayError PowerOn(int *release_fence);
   virtual DisplayError PowerOff();
-  virtual DisplayError Doze();
-  virtual DisplayError DozeSuspend();
+  virtual DisplayError Doze(int *release_fence);
+  virtual DisplayError DozeSuspend(int *release_fence);
   virtual DisplayError Standby();
   virtual DisplayError Validate(HWLayers *hw_layers);
   virtual DisplayError Commit(HWLayers *hw_layers);

sdm/libs/core/drm/hw_tv_drm.cpp

@@ -165,11 +165,11 @@ DisplayError HWTVDRM::PowerOff() {
   return kErrorNone;
 }
 
-DisplayError HWTVDRM::Doze() {
+DisplayError HWTVDRM::Doze(int *release_fence) {
   return kErrorNone;
 }
 
-DisplayError HWTVDRM::DozeSuspend() {
+DisplayError HWTVDRM::DozeSuspend(int *release_fence) {
   return kErrorNone;
 }
 

sdm/libs/core/drm/hw_tv_drm.h

@@ -43,8 +43,8 @@ class HWTVDRM : public HWDeviceDRM {
   virtual DisplayError SetDisplayAttributes(uint32_t index);
   virtual DisplayError GetConfigIndex(char *mode, uint32_t *index);
   virtual DisplayError PowerOff();
-  virtual DisplayError Doze();
-  virtual DisplayError DozeSuspend();
+  virtual DisplayError Doze(int *release_fence);
+  virtual DisplayError DozeSuspend(int *release_fence);
   virtual DisplayError Standby();
   virtual DisplayError Commit(HWLayers *hw_layers);
   virtual void PopulateHWPanelInfo();

sdm/libs/core/fb/hw_device.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -155,7 +155,7 @@ DisplayError HWDevice::GetConfigIndex(char *mode, uint32_t *index) {
   return kErrorNone;
 }
 
-DisplayError HWDevice::PowerOn() {
+DisplayError HWDevice::PowerOn(int *release_fence) {
   DTRACE_SCOPED();
 
   if (Sys::ioctl_(device_fd_, FBIOBLANK, FB_BLANK_UNBLANK) < 0) {
@@ -174,11 +174,11 @@ DisplayError HWDevice::PowerOff() {
   return kErrorNone;
 }
 
-DisplayError HWDevice::Doze() {
+DisplayError HWDevice::Doze(int *release_fence) {
   return kErrorNone;
 }
 
-DisplayError HWDevice::DozeSuspend() {
+DisplayError HWDevice::DozeSuspend(int *release_fence) {
   return kErrorNone;
 }
 

sdm/libs/core/fb/hw_device.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -70,10 +70,10 @@ class HWDevice : public HWInterface {
   virtual DisplayError SetDisplayAttributes(uint32_t index);
   virtual DisplayError SetDisplayAttributes(const HWDisplayAttributes &display_attributes);
   virtual DisplayError GetConfigIndex(char *mode, uint32_t *index);
-  virtual DisplayError PowerOn();
+  virtual DisplayError PowerOn(int *release_fence);
   virtual DisplayError PowerOff();
-  virtual DisplayError Doze();
-  virtual DisplayError DozeSuspend();
+  virtual DisplayError Doze(int *release_fence);
+  virtual DisplayError DozeSuspend(int *release_fence);
   virtual DisplayError Standby();
   virtual DisplayError Validate(HWLayers *hw_layers);
   virtual DisplayError Commit(HWLayers *hw_layers);

sdm/libs/core/fb/hw_primary.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2015 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2015 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -344,7 +344,7 @@ DisplayError HWPrimary::PowerOff() {
   return kErrorNone;
 }
 
-DisplayError HWPrimary::Doze() {
+DisplayError HWPrimary::Doze(int *release_fence) {
   if (Sys::ioctl_(device_fd_, FBIOBLANK, FB_BLANK_NORMAL) < 0) {
     IOCTL_LOGE(FB_BLANK_NORMAL, device_type_);
     return kErrorHardware;
@@ -353,7 +353,7 @@ DisplayError HWPrimary::Doze() {
   return kErrorNone;
 }
 
-DisplayError HWPrimary::DozeSuspend() {
+DisplayError HWPrimary::DozeSuspend(int *release_fence) {
   if (Sys::ioctl_(device_fd_, FBIOBLANK, FB_BLANK_VSYNC_SUSPEND) < 0) {
     IOCTL_LOGE(FB_BLANK_VSYNC_SUSPEND, device_type_);
     return kErrorHardware;

sdm/libs/core/fb/hw_primary.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.
+* Copyright (c) 2015-2016, 2018 The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -46,8 +46,8 @@ class HWPrimary : public HWDevice {
   virtual DisplayError SetDisplayAttributes(uint32_t index);
   virtual DisplayError GetConfigIndex(char *mode, uint32_t *index);
   virtual DisplayError PowerOff();
-  virtual DisplayError Doze();
-  virtual DisplayError DozeSuspend();
+  virtual DisplayError Doze(int *release_fence);
+  virtual DisplayError DozeSuspend(int *release_fence);
   virtual DisplayError Validate(HWLayers *hw_layers);
   virtual DisplayError Commit(HWLayers *hw_layers);
   virtual void SetIdleTimeoutMs(uint32_t timeout_ms);

sdm/libs/core/hw_interface.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014 - 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -85,10 +85,10 @@ class HWInterface {
   virtual DisplayError SetDisplayAttributes(uint32_t index) = 0;
   virtual DisplayError SetDisplayAttributes(const HWDisplayAttributes &display_attributes) = 0;
   virtual DisplayError GetConfigIndex(char *mode, uint32_t *index) = 0;
-  virtual DisplayError PowerOn() = 0;
+  virtual DisplayError PowerOn(int *release_fence) = 0;
   virtual DisplayError PowerOff() = 0;
-  virtual DisplayError Doze() = 0;
-  virtual DisplayError DozeSuspend() = 0;
+  virtual DisplayError Doze(int *release_fence) = 0;
+  virtual DisplayError DozeSuspend(int *release_fence) = 0;
   virtual DisplayError Standby() = 0;
   virtual DisplayError Validate(HWLayers *hw_layers) = 0;
   virtual DisplayError Commit(HWLayers *hw_layers) = 0;

sdm/libs/hwc2/display_null.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -50,7 +50,7 @@ DisplayError DisplayNull::GetDisplayState(DisplayState *state) {
   return kErrorNone;
 }
 
-DisplayError DisplayNull::SetDisplayState(DisplayState state) {
+DisplayError DisplayNull::SetDisplayState(DisplayState state, int *release_fence) {
   state_ = state;
   return kErrorNone;
 }

sdm/libs/hwc2/display_null.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -44,7 +44,7 @@ class DisplayNull : public DisplayInterface {
   virtual ~DisplayNull() { }
   virtual DisplayError Commit(LayerStack *layer_stack);
   virtual DisplayError GetDisplayState(DisplayState *state);
-  virtual DisplayError SetDisplayState(DisplayState state);
+  virtual DisplayError SetDisplayState(DisplayState state, int *release_fence);
   virtual DisplayError SetFrameBufferConfig(const DisplayConfigVariableInfo &variable_info);
   virtual DisplayError GetFrameBufferConfig(DisplayConfigVariableInfo *variable_info);
   virtual bool IsUnderscanSupported() { return true; }

sdm/libs/hwc2/hwc_display.cpp

@@ -745,9 +745,10 @@ HWC2::Error HWCDisplay::SetPowerMode(HWC2::PowerMode mode) {
     default:
       return HWC2::Error::BadParameter;
   }
+  int release_fence = -1;
 
   ATRACE_INT("SetPowerMode ", state);
-  DisplayError error = display_intf_->SetDisplayState(state);
+  DisplayError error = display_intf_->SetDisplayState(state, &release_fence);
   validated_ = false;
 
   if (error == kErrorNone) {
@@ -761,6 +762,20 @@ HWC2::Error HWCDisplay::SetPowerMode(HWC2::PowerMode mode) {
     return HWC2::Error::BadParameter;
   }
 
+  if (release_fence >= 0) {
+    for (auto hwc_layer : layer_set_) {
+      auto fence = hwc_layer->PopBackReleaseFence();
+      auto merged_fence = -1;
+      if (fence >= 0) {
+        merged_fence = sync_merge("sync_merge", release_fence, fence);
+        ::close(fence);
+      } else {
+        merged_fence = ::dup(release_fence);
+      }
+      hwc_layer->PushBackReleaseFence(merged_fence);
+    }
+    ::close(release_fence);
+  }
   return HWC2::Error::None;
 }
 
@@ -1132,7 +1147,7 @@ HWC2::Error HWCDisplay::GetReleaseFences(uint32_t *out_num_elements, hwc2_layer_
     for (uint32_t i = 0; i < *out_num_elements; i++, it++) {
       auto hwc_layer = *it;
       out_layers[i] = hwc_layer->GetId();
-      out_fences[i] = hwc_layer->PopReleaseFence();
+      out_fences[i] = hwc_layer->PopFrontReleaseFence();
     }
   } else {
     *out_num_elements = UINT32(layer_set_.size());
@@ -1303,15 +1318,15 @@ HWC2::Error HWCDisplay::PostCommitLayerStack(int32_t *out_retire_fence) {
       if (swap_interval_zero_ || layer->flags.single_buffer) {
         close(layer_buffer->release_fence_fd);
       } else if (layer->composition != kCompositionGPU) {
-        hwc_layer->PushReleaseFence(layer_buffer->release_fence_fd);
+        hwc_layer->PushBackReleaseFence(layer_buffer->release_fence_fd);
       } else {
-        hwc_layer->PushReleaseFence(-1);
+        hwc_layer->PushBackReleaseFence(-1);
       }
     } else {
       // In case of flush, we don't return an error to f/w, so it will get a release fence out of
       // the hwc_layer's release fence queue. We should push a -1 to preserve release fence
       // circulation semantics.
-      hwc_layer->PushReleaseFence(-1);
+      hwc_layer->PushBackReleaseFence(-1);
     }
 
     layer_buffer->release_fence_fd = -1;

sdm/libs/hwc2/hwc_display_external.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
@@ -238,9 +238,12 @@ int HWCDisplayExternal::SetState(bool connected) {
         DLOGW("Set frame buffer config failed. Error = %d", error);
         return -1;
       }
-
+      int release_fence = -1;
       display_null_.GetDisplayState(&state);
-      display_intf_->SetDisplayState(state);
+      display_intf_->SetDisplayState(state, &release_fence);
+      if (release_fence >= 0) {
+        ::close(release_fence);
+      }
       validated_ = false;
 
       SetVsyncEnabled(HWC2::Vsync::Enable);
@@ -252,10 +255,14 @@ int HWCDisplayExternal::SetState(bool connected) {
     }
   } else {
     if (!display_null_.IsActive()) {
+      int release_fence = -1;
       // Preserve required attributes of HDMI display that surfaceflinger sees.
       // Restore HDMI attributes when display is reconnected.
       display_intf_->GetDisplayState(&state);
-      display_null_.SetDisplayState(state);
+      display_null_.SetDisplayState(state, &release_fence);
+      if (release_fence >= 0) {
+        ::close(release_fence);
+      }
 
       error = display_intf_->GetFrameBufferConfig(&fb_config);
       if (error != kErrorNone) {

sdm/libs/hwc2/hwc_layers.cpp

@@ -170,14 +170,14 @@ HWCLayer::HWCLayer(hwc2_display_t display_id, HWCBufferAllocator *buf_allocator)
   layer_ = new Layer();
   // Fences are deferred, so the first time this layer is presented, return -1
   // TODO(user): Verify that fences are properly obtained on suspend/resume
-  release_fences_.push(-1);
+  release_fences_.push_back(-1);
 }
 
 HWCLayer::~HWCLayer() {
   // Close any fences left for this layer
   while (!release_fences_.empty()) {
     ::close(release_fences_.front());
-    release_fences_.pop();
+    release_fences_.pop_front();
   }
   if (layer_) {
     if (layer_->input_buffer.acquire_fence_fd >= 0) {
@@ -887,14 +887,28 @@ void HWCLayer::SetComposition(const LayerComposition &sdm_composition) {
 
   return;
 }
-void HWCLayer::PushReleaseFence(int32_t fence) {
-  release_fences_.push(fence);
+
+void HWCLayer::PushBackReleaseFence(int32_t fence) {
+  release_fences_.push_back(fence);
 }
-int32_t HWCLayer::PopReleaseFence(void) {
+
+int32_t HWCLayer::PopBackReleaseFence() {
   if (release_fences_.empty())
     return -1;
+
+  auto fence = release_fences_.back();
+  release_fences_.pop_back();
+
+  return fence;
+}
+
+int32_t HWCLayer::PopFrontReleaseFence() {
+  if (release_fences_.empty())
+    return -1;
+
   auto fence = release_fences_.front();
-  release_fences_.pop();
+  release_fences_.pop_front();
+
   return fence;
 }
 

sdm/libs/hwc2/hwc_layers.h

@@ -32,7 +32,7 @@
 #undef HWC2_INCLUDE_STRINGIFICATION
 #undef HWC2_USE_CPP11
 #include <map>
-#include <queue>
+#include <deque>
 #include <set>
 #include "core/buffer_allocator.h"
 #include "hwc_buffer_allocator.h"
@@ -88,8 +88,9 @@ class HWCLayer {
   int32_t GetLayerDataspace() { return dataspace_; }
   uint32_t GetGeometryChanges() { return geometry_changes_; }
   void ResetGeometryChanges() { geometry_changes_ = GeometryChanges::kNone; }
-  void PushReleaseFence(int32_t fence);
-  int32_t PopReleaseFence(void);
+  void PushBackReleaseFence(int32_t fence);
+  int32_t PopBackReleaseFence(void);
+  int32_t PopFrontReleaseFence(void);
   bool ValidateAndSetCSC();
   bool SupportLocalConversion(ColorPrimaries working_primaries);
   void ResetValidation() { needs_validate_ = false; }
@@ -105,7 +106,7 @@ class HWCLayer {
   const hwc2_layer_t id_;
   const hwc2_display_t display_id_;
   static std::atomic<hwc2_layer_t> next_id_;
-  std::queue<int32_t> release_fences_;
+  std::deque<int32_t> release_fences_;
   HWCBufferAllocator *buffer_allocator_ = NULL;
   int32_t dataspace_ =  HAL_DATASPACE_UNKNOWN;
   LayerTransform layer_transform_ = {};