commit 45da457cb00d565d00bb0f250a2c39f61927b6f7
author Dileep Kumar Reddi <dkumarre@codeaurora.org> Tue Apr 21 08:29:25 2015 +0530
committer Gerrit - the friendly Code Review server <code-review@localhost> Tue Apr 21 19:43:39 2015 -0700
tree 2731a446e11bad2e46b66787a7f1125fd5e567d9
parent cdc229e2a62f347bccf1686714537460e19050f9

hwc: Do not compose when there is no update in Frame content

No need to blit layers when there is no change in content in successive
frames, so we can avoid those blits to achieve power and performance
improvements. For example screen-refresh triggered by pp-daemon.

Change-Id: Ie992705fa3d7f1ceba3d55b4865b017cfeafb34f

libhwcomposer/hwc_copybit.cpp

diff --git a/libhwcomposer/hwc_copybit.cpp b/libhwcomposer/hwc_copybit.cpp
index e223ff4..00bd643 100644
--- a/libhwcomposer/hwc_copybit.cpp
+++ b/libhwcomposer/hwc_copybit.cpp
@@ -174,11 +174,20 @@
     //dirty rect for same layer at least equal of number of
     //framebuffers
 
-    if ( updatingLayerCount ==  1 ) {
-       hwc_rect_t dirtyRect = list->hwLayers[changingLayerIndex].displayFrame;
+    if ( updatingLayerCount <=  1 ) {
+        hwc_rect_t dirtyRect;
+        if (updatingLayerCount == 0) {
+            dirtyRect.left = INVALID_DIMENSION;
+            dirtyRect.top = INVALID_DIMENSION;
+            dirtyRect.right = INVALID_DIMENSION;
+            dirtyRect.bottom = INVALID_DIMENSION;
+            changingLayerIndex = NO_UPDATING_LAYER;
+        } else {
+            dirtyRect = list->hwLayers[changingLayerIndex].displayFrame;
 #ifdef QCOM_BSP
-       dirtyRect = list->hwLayers[changingLayerIndex].dirtyRect;
+            dirtyRect = list->hwLayers[changingLayerIndex].dirtyRect;
 #endif
+        }
 
        for (int k = ctx->listStats[dpy].numAppLayers-1; k >= 0 ; k--) {
            //disable swap rect in case of scaling and video .
@@ -553,11 +562,13 @@
     mDirtyLayerIndex =  checkDirtyRect(ctx, list, dpy);
     ALOGD_IF (DEBUG_COPYBIT, "%s:Dirty Layer Index: %d",
                                        __FUNCTION__, mDirtyLayerIndex);
+
     hwc_rect_t clearRegion = {0,0,0,0};
     mDirtyRect = list->hwLayers[last].displayFrame;
 
-    if (CBUtils::getuiClearRegion(list, clearRegion, layerProp,
-                                                       mDirtyLayerIndex)) {
+    if (mDirtyLayerIndex != NO_UPDATING_LAYER &&
+            CBUtils::getuiClearRegion(list, clearRegion, layerProp,
+                                                    mDirtyLayerIndex)) {
        int clear_w =  clearRegion.right -  clearRegion.left;
        int clear_h =  clearRegion.bottom - clearRegion.top;
        //mdp can't handle solid fill for one line
@@ -569,8 +580,13 @@
        }else
            clear(renderBuffer, clearRegion);
     }
-    if (mDirtyLayerIndex != -1)
-           mDirtyRect = list->hwLayers[mDirtyLayerIndex].displayFrame;
+    if (mDirtyLayerIndex != -1) {
+        if (mDirtyLayerIndex == NO_UPDATING_LAYER) {
+            mDirtyRect = clearRegion;
+        } else {
+            mDirtyRect = list->hwLayers[mDirtyLayerIndex].displayFrame;
+        }
+    }
 
     // numAppLayers-1, as we iterate from 0th layer index with HWC_COPYBIT flag
     for (int i = 0; i <= (ctx->listStats[dpy].numAppLayers-1); i++) {