commit b1c7632ec53d3ba4d65643936b61e83c4cd63376
author Naseer Ahmed <naseer@codeaurora.org> Wed Oct 17 00:32:50 2012 -0400
committer Naseer Ahmed <naseer@codeaurora.org> Mon Dec 03 15:32:29 2012 -0500
tree 42e91ed379f2066f4f3ac40d285da45899473816
parent 09549f6d757194761ea26dc0bd0717b851d8f067

hwc: cache layers on framebuffer

In the cases where all the layers that are marked as HWC_FRAMEBUFFER did not
change, we can mark them as HWC_OVERLAY since their contents are already on the
framebuffer and do not need any additional processing.

This optimization shows power improvement for video playback.

Bug: 7623741
Change-Id: Ia178a926e6f56a3ec9291250a22a66f212c30b14
Signed-off-by: Iliyan Malchev <malchev@google.com>

libhwcomposer/hwc.cpp

diff --git a/libhwcomposer/hwc.cpp b/libhwcomposer/hwc.cpp
index a2ea3c9..a63aed7 100644
--- a/libhwcomposer/hwc.cpp
+++ b/libhwcomposer/hwc.cpp
@@ -77,11 +77,23 @@
 }
 
 //Helper
-static void reset(hwc_context_t *ctx, int numDisplays) {
+static void reset(hwc_context_t *ctx, int numDisplays,
+                  hwc_display_contents_1_t** displays) {
     memset(ctx->listStats, 0, sizeof(ctx->listStats));
     for(int i = 0; i < HWC_NUM_DISPLAY_TYPES; i++){
         ctx->overlayInUse[i] = false;
         ctx->listStats[i].yuvIndex = -1;
+        hwc_display_contents_1_t *list = displays[i];
+        // XXX:SurfaceFlinger no longer guarantees that this
+        // value is reset on every prepare. However, for the layer
+        // cache we need to reset it.
+        // We can probably rethink that later on
+        if (LIKELY(list && list->numHwLayers > 1)) {
+            for(uint32_t j = 0; j < list->numHwLayers; j++) {
+                if(list->hwLayers[j].compositionType != HWC_FRAMEBUFFER_TARGET)
+                    list->hwLayers[j].compositionType = HWC_FRAMEBUFFER;
+            }
+        }
     }
 }
 
@@ -103,6 +115,7 @@
             } else {
                 ctx->overlayInUse[HWC_DISPLAY_PRIMARY] = false;
             }
+            ctx->mLayerCache->updateLayerCache(list);
         }
     }
     return 0;
@@ -141,7 +154,7 @@
 {
     int ret = 0;
     hwc_context_t* ctx = (hwc_context_t*)(dev);
-    reset(ctx, numDisplays);
+    reset(ctx, numDisplays, displays);
 
     //If securing of h/w in progress skip comp using overlay.
     if(ctx->mSecuring == true) return 0;