drm_hwcomposer: Make flattening thread-based instead of vsync-based

Using vsync means consume some CPU time every frame for
IRQ -> Kernel_Thread -> UserSpace_listener thread transitions.

Framework tries to reduce vsync usage to the minimum, by using timelines
instead.

New flattening controller thread wakes-up only once per second.

This commit also removes flattening info from dumpsys. Practice shows
that it is almost useless. Instead debugging can be done using ALOGV
dumps.

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>

2 files changed, 18 insertions, 73 deletions

diff --git a/hwc2_device/HwcDisplay.cpp b/hwc2_device/HwcDisplay.cpp
index cdcf518..13da016 100644
--- a/hwc2_device/HwcDisplay.cpp
+++ b/hwc2_device/HwcDisplay.cpp
@@ -50,32 +50,12 @@ std::string HwcDisplay::DumpDelta(HwcDisplay::Stats delta) {
 }
 
 std::string HwcDisplay::Dump() {
-  std::string flattening_state_str;
-  switch (flattenning_state_) {
-    case ClientFlattenningState::Disabled:
-      flattening_state_str = "Disabled";
-      break;
-    case ClientFlattenningState::NotRequired:
-      flattening_state_str = "Not needed";
-      break;
-    case ClientFlattenningState::Flattened:
-      flattening_state_str = "Active";
-      break;
-    case ClientFlattenningState::ClientRefreshRequested:
-      flattening_state_str = "Refresh requested";
-      break;
-    default:
-      flattening_state_str = std::to_string(flattenning_state_) +
-                             " VSync remains";
-  }
-
   auto connector_name = IsInHeadlessMode()
                             ? std::string("NULL-DISPLAY")
                             : GetPipe().connector->Get()->GetName();
 
   std::stringstream ss;
   ss << "- Display on: " << connector_name << "\n"
-     << "  Flattening state: " << flattening_state_str << "\n"
      << "Statistics since system boot:\n"
      << DumpDelta(total_stats_) << "\n\n"
      << "Statistics since last dumpsys request:\n"
@@ -140,6 +120,10 @@ void HwcDisplay::Deinit() {
 
     current_plan_.reset();
     backend_.reset();
+    if (flatcon_) {
+      flatcon_->StopThread();
+      flatcon_.reset();
+    }
   }
 
   if (vsync_worker_) {
@@ -162,14 +146,10 @@ HWC2::Error HwcDisplay::Init() {
               GetDisplayVsyncPeriod(&period_ns);
               hwc2_->SendVsyncEventToClient(handle_, timestamp, period_ns);
             }
-            if (vsync_flattening_en_) {
-              ProcessFlatenningVsyncInternal();
-            }
             if (vsync_tracking_en_) {
               last_vsync_ts_ = timestamp;
             }
-            if (!vsync_event_en_ && !vsync_flattening_en_ &&
-                !vsync_tracking_en_) {
+            if (!vsync_event_en_ && !vsync_tracking_en_) {
               vsync_worker_->VSyncControl(false);
             }
           },
@@ -192,6 +172,13 @@ HWC2::Error HwcDisplay::Init() {
       ALOGE("Failed to set backend for d=%d %d\n", int(handle_), ret);
       return HWC2::Error::BadDisplay;
     }
+    auto flatcbk = (struct FlatConCallbacks){.trigger = [this]() {
+      if (hwc2_->refresh_callback_.first != nullptr &&
+          hwc2_->refresh_callback_.second != nullptr)
+        hwc2_->refresh_callback_.first(hwc2_->refresh_callback_.second,
+                                       handle_);
+    }};
+    flatcon_ = FlatteningController::CreateInstance(flatcbk);
   }
 
   client_layer_.SetLayerBlendMode(HWC2_BLEND_MODE_PREMULTIPLIED);
@@ -1022,37 +1009,4 @@ void HwcDisplay::set_backend(std::unique_ptr<Backend> backend) {
   backend_ = std::move(backend);
 }
 
-/* returns true if composition should be sent to client */
-bool HwcDisplay::ProcessClientFlatteningState(bool skip) {
-  const int flattenning_state = flattenning_state_;
-  if (flattenning_state == ClientFlattenningState::Disabled) {
-    return false;
-  }
-
-  if (skip) {
-    flattenning_state_ = ClientFlattenningState::NotRequired;
-    return false;
-  }
-
-  if (flattenning_state == ClientFlattenningState::ClientRefreshRequested) {
-    flattenning_state_ = ClientFlattenningState::Flattened;
-    return true;
-  }
-
-  vsync_flattening_en_ = true;
-  vsync_worker_->VSyncControl(true);
-  flattenning_state_ = ClientFlattenningState::VsyncCountdownMax;
-  return false;
-}
-
-void HwcDisplay::ProcessFlatenningVsyncInternal() {
-  if (flattenning_state_ > ClientFlattenningState::ClientRefreshRequested &&
-      --flattenning_state_ == ClientFlattenningState::ClientRefreshRequested &&
-      hwc2_->refresh_callback_.first != nullptr &&
-      hwc2_->refresh_callback_.second != nullptr) {
-    hwc2_->refresh_callback_.first(hwc2_->refresh_callback_.second, handle_);
-    vsync_flattening_en_ = false;
-  }
-}
-
 }  // namespace android
diff --git a/hwc2_device/HwcDisplay.h b/hwc2_device/HwcDisplay.h
index 653aa4a..bf95c3e 100644
--- a/hwc2_device/HwcDisplay.h
+++ b/hwc2_device/HwcDisplay.h
@@ -23,6 +23,7 @@
 #include <sstream>
 
 #include "HwcDisplayConfigs.h"
+#include "compositor/FlatteningController.h"
 #include "compositor/LayerData.h"
 #include "drm/DrmAtomicStateManager.h"
 #include "drm/ResourceManager.h"
@@ -165,10 +166,6 @@ class HwcDisplay {
     return total_stats_;
   }
 
-  /* returns true if composition should be sent to client */
-  bool ProcessClientFlatteningState(bool skip);
-  void ProcessFlatenningVsyncInternal();
-
   /* Headless mode required to keep SurfaceFlinger alive when all display are
    * disconnected, Without headless mode Android will continuously crash.
    * Only single internal (primary) display is required to be in HEADLESS mode
@@ -181,17 +178,11 @@ class HwcDisplay {
 
   void Deinit();
 
- private:
-  enum ClientFlattenningState : int32_t {
-    Disabled = -3,
-    NotRequired = -2,
-    Flattened = -1,
-    ClientRefreshRequested = 0,
-    VsyncCountdownMax = 60, /* 1 sec @ 60FPS */
-  };
-
-  std::atomic_int flattenning_state_{ClientFlattenningState::NotRequired};
+  auto GetFlatCon() {
+    return flatcon_;
+  }
 
+ private:
   HwcDisplayConfigs configs_;
 
   DrmHwcTwo *const hwc2_;
@@ -205,10 +196,10 @@ class HwcDisplay {
   DrmDisplayPipeline *pipeline_{};
 
   std::unique_ptr<Backend> backend_;
+  std::shared_ptr<FlatteningController> flatcon_;
 
   std::shared_ptr<VSyncWorker> vsync_worker_;
   bool vsync_event_en_{};
-  bool vsync_flattening_en_{};
   bool vsync_tracking_en_{};
   int64_t last_vsync_ts_{};