SurfaceFlinger: Change to support framebuffer flip for 2D blitters

- Surfaceflinger does not flip framebuffers when there are
  no layers marked for HWC_FRAMEBUFFER
- This change checks for the HWC_BLIT flag and will request a flip
  to a new FB_TARGET buffer even if there are no FRAMEBUFFER layers

Change-Id: I1cb44389a05c9ec049d7f0d39c288feccb11a91c

2 files changed, 9 insertions, 0 deletions

diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 690ec8d..379fb16 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -776,6 +776,11 @@ status_t HWComposer::prepare() {
                     if (l.compositionType == HWC_FRAMEBUFFER) {
                         disp.hasFbComp = true;
                     }
+                    // If the composition type is BLIT, we set this to
+                    // trigger a FLIP
+                    if(l.compositionType == HWC_BLIT) {
+                        disp.hasFbComp = true;
+                    }
                     if (l.compositionType == HWC_OVERLAY) {
                         disp.hasOvComp = true;
                     }
@@ -1232,6 +1237,7 @@ void HWComposer::dump(String8& result, char* buffer, size_t SIZE) const {
                             "HWC",
                             "BACKGROUND",
                             "FB TARGET",
+                            "FB_BLIT",
                             "UNKNOWN"};
                     if (type >= NELEM(compositionTypeName))
                         type = NELEM(compositionTypeName) - 1;
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 6d8f558..67b1316 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1576,6 +1576,9 @@ void SurfaceFlinger::doComposeSurfaces(const sp<const DisplayDevice>& hw, const
                         layer->draw(hw, clip);
                         break;
                     }
+                    case HWC_BLIT:
+                        //Do nothing
+                        break;
                     case HWC_FRAMEBUFFER_TARGET: {
                         // this should not happen as the iterator shouldn't
                         // let us get there.