Add FlattenReason to Backend

This change adds a new enum FlattenReason which
describes possible reasons that a given composition
would be flattened. The flatten reason is now
returned with the ValidationComposition.

Change-Id: Ia7ba2ffbdc3512fea9cb19ab6be63a99eaa3f367

backend/Backend.cpp

@@ -17,12 +17,13 @@
 
 #include "Backend.h"
 
-#include <climits>
+#include <tuple>
+#include <vector>
 
 #include "BackendManager.h"
-#include "bufferinfo/BufferInfoGetter.h"
-#include "drm/DrmHwc.h"
+#include "compositor/LayerData.h"
 #include "hwc/HwcDisplay.h"
+#include "hwc/HwcLayer.h"
 
 namespace android::drm_hwcomposer {
 
@@ -43,14 +44,12 @@ const HwcLayer* GetCursorLayer(const std::vector<const HwcLayer*>& layers) {
 }  // namespace
 
 auto Backend::ValidateDisplay(HwcDisplay* display) -> ValidatedComposition {
-  auto layers = display->GetOrderLayersByZPos();
+  const auto layers = display->GetOrderLayersByZPos();
 
   const FlatteningController* flatcon = display->GetFlatCon();
-  if (flatcon != nullptr) {
-    if (flatcon->ShouldFlatten()) {
-      display->total_stats().frames_flattened++;
-      return GetFlattenedComposition(layers);
-    }
+  if (flatcon != nullptr && flatcon->ShouldFlatten()) {
+    display->total_stats().frames_flattened++;
+    return GetFlattenedComposition(layers, FlattenReason::kStaticScene);
   }
 
   bool use_cursor_plane = false;
@@ -69,7 +68,7 @@ auto Backend::ValidateDisplay(HwcDisplay* display) -> ValidatedComposition {
 
   size_t client_start = 0;
   size_t client_size = 0;
-  ValidatedComposition validated_composition;
+  ValidatedComposition validated_composition{};
 
   // Populates and tests |validated_composition|, returning whether it
   // succeeded.
@@ -115,7 +114,11 @@ auto Backend::ValidateDisplay(HwcDisplay* display) -> ValidatedComposition {
       ++display->total_stats().failed_kms_cursor_validate;
     }
     use_cursor_plane = false;
-    validated_composition = GetFlattenedComposition(layers);
+    validated_composition = GetFlattenedComposition(layers,
+                                                    FlattenReason::
+                                                        kValidateFailed);
+  } else if (display->CtmByGpu()) {
+    validated_composition.flatten_reason = FlattenReason::kCtmWithOffset;
   }
 
   display->total_stats().gpu_pixops += CalcPixOps(validated_composition);
@@ -127,10 +130,11 @@ auto Backend::ValidateDisplay(HwcDisplay* display) -> ValidatedComposition {
 }
 
 Backend::ValidatedComposition Backend::GetFlattenedComposition(
-    const std::vector<const HwcLayer*>& layers) {
+    const std::vector<const HwcLayer*>& layers, FlattenReason flatten_reason) {
   return ValidatedComposition{
       .composition_types = GetCompositionTypes(layers, 0, layers.size(), false),
-      .composition_plan = nullptr};
+      .composition_plan = nullptr,
+      .flatten_reason = flatten_reason};
 }
 
 std::tuple<size_t, size_t> Backend::GetClientLayers(

backend/Backend.h

@@ -17,6 +17,8 @@
 #pragma once
 
 #include <map>
+#include <memory>
+#include <tuple>
 #include <vector>
 
 #include "compositor/LayerData.h"
@@ -32,6 +34,15 @@ class Backend {
   // Mapping of the CompositionType that the Backend assigned to each
   // HwcLayer.
   using CompositionTypeMap = std::map<const HwcLayer*, CompositionType>;
+  // Enum of possible reasons that the backend may choose to flatten the
+  // composition.
+  enum class FlattenReason {
+    kUnspecified = 0,
+    kNone,
+    kStaticScene,
+    kValidateFailed,
+    kCtmWithOffset,
+  };
   struct ValidatedComposition {
     // The resulting composition type for each layer.
     CompositionTypeMap composition_types{};
@@ -40,6 +51,8 @@ class Backend {
     // for use by this display. As such, the caller must ensure that the
     // DrmKmsPlan is not destructed before the composition is committed.
     std::shared_ptr<DrmKmsPlan> composition_plan = nullptr;
+    // Reason the composition was flattened, or |kNone| if it wasn't.
+    FlattenReason flatten_reason = FlattenReason::kNone;
   };
 
   virtual ~Backend() = default;
@@ -51,7 +64,7 @@ class Backend {
 
  protected:
   static ValidatedComposition GetFlattenedComposition(
-      const std::vector<const HwcLayer*>& layers);
+      const std::vector<const HwcLayer*>& layers, FlattenReason flatten_reason);
   static bool HardwareSupportsLayerType(CompositionType comp_type);
   static uint32_t CalcPixOps(const ValidatedComposition& validated_composition);
   static uint32_t CalcPixOps(const std::vector<const HwcLayer*>& layers,

backend/BackendClient.cpp

@@ -23,7 +23,8 @@ namespace android::drm_hwcomposer {
 
 auto BackendClient::ValidateDisplay(HwcDisplay* display)
     -> ValidatedComposition {
-  return GetFlattenedComposition(display->GetOrderLayersByZPos());
+  return GetFlattenedComposition(display->GetOrderLayersByZPos(),
+                                 FlattenReason::kNone);
 }
 
 // clang-format off