Snap for 8010657 from 0b5ab223e110f3a34b30e7b61e4ea68c03dba98b to sc-v2-release

Change-Id: Ie66e88133267b6c910002995e0dbc92f326155cd
diff --git a/modules/gralloc/Android.mk b/modules/gralloc/Android.mk
index 439c95d..4c4899e 100644
--- a/modules/gralloc/Android.mk
+++ b/modules/gralloc/Android.mk
@@ -38,5 +38,8 @@
 ifeq ($(TARGET_USE_PAN_DISPLAY),true)
 LOCAL_CFLAGS += -DUSE_PAN_DISPLAY=1
 endif
+ifneq ($(GRALLOC_FRAMEBUFFER_NUM),)
+LOCAL_CFLAGS += -DNUM_BUFFERS=$(GRALLOC_FRAMEBUFFER_NUM)
+endif
 
 include $(BUILD_SHARED_LIBRARY)
diff --git a/modules/gralloc/framebuffer.cpp b/modules/gralloc/framebuffer.cpp
index b2ec3e4..fc220db 100644
--- a/modules/gralloc/framebuffer.cpp
+++ b/modules/gralloc/framebuffer.cpp
@@ -45,8 +45,10 @@
 #define USE_PAN_DISPLAY 0
 #endif
 
-// numbers of buffers for page flipping
+// Enabling page flipping by default
+#ifndef NUM_BUFFERS
 #define NUM_BUFFERS 2
+#endif
 
 
 enum {
@@ -157,7 +159,8 @@
     info.activate = FB_ACTIVATE_NOW;
 
     /*
-     * Request NUM_BUFFERS screens (at lest 2 for page flipping)
+     * Request NUM_BUFFERS screens
+     * To enable page flipping, NUM_BUFFERS should be at least 2.
      */
     info.yres_virtual = info.yres * NUM_BUFFERS;