SurfaceFlinger: use async mode for video & cam

This change makes SurfaceFlinger's SurfaceTexture objects default to
async mode whenever a camera or video decoder connects.  This behavior
can be disabled by #defining NEVER_DEFAULT_TO_ASYNC_MODE.

Change-Id: I8965951d1775915da180e4af298dd7af3afafecc

services/surfaceflinger/Android.mk

@@ -22,7 +22,7 @@ ifeq ($(TARGET_BOARD_PLATFORM), omap3)
 	LOCAL_CFLAGS += -DNO_RGBX_8888
 endif
 ifeq ($(TARGET_BOARD_PLATFORM), s5pc110)
-	LOCAL_CFLAGS += -DHAS_CONTEXT_PRIORITY
+	LOCAL_CFLAGS += -DHAS_CONTEXT_PRIORITY -DNEVER_DEFAULT_TO_ASYNC_MODE
 endif
 
 

services/surfaceflinger/SurfaceTextureLayer.cpp

@@ -86,6 +86,32 @@ status_t SurfaceTextureLayer::dequeueBuffer(int *buf,
     return res;
 }
 
+status_t SurfaceTextureLayer::connect(int api) {
+    status_t err = SurfaceTexture::connect(api);
+    if (err == NO_ERROR) {
+        switch(api) {
+            case NATIVE_WINDOW_API_MEDIA:
+            case NATIVE_WINDOW_API_CAMERA:
+                // Camera preview and videos are rate-limited on the producer
+                // side.  If enabled for this build, we use async mode to always
+                // show the most recent frame at the cost of requiring an
+                // additional buffer.
+#ifndef NEVER_DEFAULT_TO_ASYNC_MODE
+                err = setSynchronousMode(false);
+                break;
+#endif
+                // fall through to set synchronous mode when not defaulting to
+                // async mode.
+            deafult:
+                err = setSynchronousMode(true);
+                break;
+        }
+        if (err != NO_ERROR) {
+            disconnect(api);
+        }
+    }
+    return err;
+}
 
 // ---------------------------------------------------------------------------
 }; // namespace android

services/surfaceflinger/SurfaceTextureLayer.h

@@ -50,6 +50,8 @@ protected:
 
     virtual status_t dequeueBuffer(int *buf, uint32_t w, uint32_t h,
             uint32_t format, uint32_t usage);
+
+    virtual status_t connect(int api);
 };
 
 // ---------------------------------------------------------------------------