Add GRALLOC_FRAMEBUFFER_NUM configuration
Add config to set the NUM_BUFFERS. Set NUM_BUFFERS to 1 can
prevent page flipping and set it to a larger number can allow
userspace to fill up the following frame earlier.
Bug: 205917753
Change-Id: Ibf4a52a1e35f4a2404008a48b637cb82c4b46365
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;