sf: Clear FrameBuffer only if there are GLES composed layers

Clear FrameBuffer Target only if there are layers to be composed by
GLES. Otherwise, it results unnecessary gl calls and increases power
consumption in full MDP comp use cases.

Change-Id: Ib84c4fe154bb67668e4e8b8ce2f2328c55aed7c6

1 files changed, 16 insertions, 13 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 4f7b54933..e7c471615 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2120,20 +2120,23 @@ void SurfaceFlinger::doComposeSurfaces(const sp<const DisplayDevice>& hw, const
                 hw->eglSwapPreserved(false);
             }
             // DrawWormHole/Any Draw has to be within startTile & EndTile
-            if (hasHwcComposition) {
-                if(mCanUseGpuTileRender && !mUnionDirtyRect.isEmpty()) {
-                    const Rect& scissor(mUnionDirtyRect);
-                    engine.setScissor(scissor.left, hw->getHeight()- scissor.bottom,
-                    scissor.getWidth(), scissor.getHeight());
-                    engine.clearWithColor(0, 0, 0, 0);
-                    engine.disableScissor();
+            if (hasGlesComposition) {
+                if (hasHwcComposition) {
+                    if(mCanUseGpuTileRender && !mUnionDirtyRect.isEmpty()) {
+                        const Rect& scissor(mUnionDirtyRect);
+                        engine.setScissor(scissor.left,
+                              hw->getHeight()- scissor.bottom,
+                              scissor.getWidth(), scissor.getHeight());
+                        engine.clearWithColor(0, 0, 0, 0);
+                        engine.disableScissor();
+                    } else {
+                        engine.clearWithColor(0, 0, 0, 0);
+                    }
                 } else {
-                    engine.clearWithColor(0, 0, 0, 0);
-                }
-            } else {
-                if (cur->getCompositionType() != HWC_BLIT &&
-                      !clearRegion.isEmpty()){
-                    drawWormhole(hw, clearRegion);
+                    if (cur->getCompositionType() != HWC_BLIT &&
+                          !clearRegion.isEmpty()){
+                        drawWormhole(hw, clearRegion);
+                    }
                 }
             }
         }