configstore: add new configuration item

This change adds to configstore@1.0 HAL a new configuration item
for surfaceflinger; useTripleFramebuffer()

In the default implementation, useTripleFramebuffer() will return true
only if the build flag NUM_FRAMEBUFFER_SURFACE_BUFFERS is defined as 3.

Bug: 34723491
Test: build & run. log message "SurfaceFlinger FrameBuffer: ?"
      should be seen.

Change-Id: Iac97e25cd69717c73a135f6b2a44538124544987
diff --git a/configstore/1.0/ISurfaceFlingerConfigs.hal b/configstore/1.0/ISurfaceFlingerConfigs.hal
index 97dc915..4403a90 100644
--- a/configstore/1.0/ISurfaceFlingerConfigs.hal
+++ b/configstore/1.0/ISurfaceFlingerConfigs.hal
@@ -17,4 +17,5 @@
 
 interface ISurfaceFlingerConfigs {
     vsyncEventPhaseOffsetNs() generates (OptionalInt64 value);
+    useTripleFramebuffer() generates (OptionalBool value);
 };
diff --git a/configstore/1.0/default/SurfaceFlingerConfigs.cpp b/configstore/1.0/default/SurfaceFlingerConfigs.cpp
index fc75182..5d62b15 100644
--- a/configstore/1.0/default/SurfaceFlingerConfigs.cpp
+++ b/configstore/1.0/default/SurfaceFlingerConfigs.cpp
@@ -19,6 +19,15 @@
     return Void();
 }
 
+Return<void> SurfaceFlingerConfigs::useTripleFramebuffer(useTripleFramebuffer_cb _hidl_cb) {
+    bool value = false;
+#ifdef USE_TRIPLE_FRAMEBUFFER
+    value = true;
+#endif
+    _hidl_cb({true, value});
+    LOG(INFO) << "SurfaceFlinger FrameBuffer: " << (value ? "triple" : "double");
+    return Void();
+}
 
 // Methods from ::android::hidl::base::V1_0::IBase follow.
 
diff --git a/configstore/1.0/default/SurfaceFlingerConfigs.h b/configstore/1.0/default/SurfaceFlingerConfigs.h
index 5c754a0..c9652fc 100644
--- a/configstore/1.0/default/SurfaceFlingerConfigs.h
+++ b/configstore/1.0/default/SurfaceFlingerConfigs.h
@@ -25,6 +25,7 @@
 struct SurfaceFlingerConfigs : public ISurfaceFlingerConfigs {
     // Methods from ::android::hardware::configstore::V1_0::ISurfaceFlingerConfigs follow.
     Return<void> vsyncEventPhaseOffsetNs(vsyncEventPhaseOffsetNs_cb _hidl_cb) override;
+    Return<void> useTripleFramebuffer(useTripleFramebuffer_cb _hidl_cb) override;
 
     // Methods from ::android::hidl::base::V1_0::IBase follow.
 
diff --git a/configstore/1.0/default/surfaceflinger.mk b/configstore/1.0/default/surfaceflinger.mk
index 42fa191..5a946f4 100644
--- a/configstore/1.0/default/surfaceflinger.mk
+++ b/configstore/1.0/default/surfaceflinger.mk
@@ -4,3 +4,7 @@
 ifneq ($(VSYNC_EVENT_PHASE_OFFSET_NS),)
     LOCAL_CFLAGS += -DVSYNC_EVENT_PHASE_OFFSET_NS=$(VSYNC_EVENT_PHASE_OFFSET_NS)
 endif
+
+ifeq ($(NUM_FRAMEBUFFER_SURFACE_BUFFERS),3)
+    LOCAL_CFLAGS += -DUSE_TRIPLE_FRAMEBUFFER
+endif