enable ALLOW_DEQUEUE_CURRENT_BUFFER for tegra devices

this flag should be enabled for all targets, but currently
some have issues with it, so we're turning it on only for
tested targets.

this will hopefully resolve some performance issues.

Bug: 5553562, 5631630
Change-Id: I54c7a9e2068586898ab13e405d95534669260537

Author: pixelflinger

libs/gui/Android.mk

@@ -32,6 +32,10 @@ LOCAL_SHARED_LIBRARIES := \
 
 LOCAL_MODULE:= libgui
 
+ifeq ($(TARGET_BOARD_PLATFORM), tegra)
+	LOCAL_CFLAGS += -DALLOW_DEQUEUE_CURRENT_BUFFER
+endif
+
 include $(BUILD_SHARED_LIBRARY)
 
 ifeq (,$(ONE_SHOT_MAKEFILE))

libs/gui/SurfaceTexture.cpp

@@ -36,8 +36,12 @@
 #include <utils/Log.h>
 #include <utils/String8.h>
 
-
-#define ALLOW_DEQUEUE_CURRENT_BUFFER    false
+#ifdef ALLOW_DEQUEUE_CURRENT_BUFFER
+#define FLAG_ALLOW_DEQUEUE_CURRENT_BUFFER    true
+#warning "ALLOW_DEQUEUE_CURRENT_BUFFER enabled"
+#else
+#define FLAG_ALLOW_DEQUEUE_CURRENT_BUFFER    false
+#endif
 
 // Macros for including the SurfaceTexture name in log messages
 #define ST_LOGV(x, ...) LOGV("[%s] "x, mName.string(), ##__VA_ARGS__)
@@ -325,7 +329,7 @@ status_t SurfaceTexture::dequeueBuffer(int *outBuf, uint32_t w, uint32_t h,
             LOGW_IF((state == BufferSlot::FREE) && (mCurrentTexture==i),
                     "dequeueBuffer: buffer %d is both FREE and current!", i);
 
-            if (ALLOW_DEQUEUE_CURRENT_BUFFER) {
+            if (FLAG_ALLOW_DEQUEUE_CURRENT_BUFFER) {
                 if (state == BufferSlot::FREE || i == mCurrentTexture) {
                     foundSync = i;
                     if (i != mCurrentTexture) {