drm_hwcomposer: have DrmDisplayCompositor do its own OpenGL composition

To accomplish this a few things changed:
- DrmComposition::GetRemainingLayers always returns the number of planes needed
- DrmComposition::AddLayer succeeds even if no DrmPlane was found for it
- DrmDisplayComposition::AddLayer has overload that imports the given buffer
- GLWorkerCompositor has a function to finish its composite before returning

Put together this change makes DrmComposition always accepts all layers given to
it even if it means some of those layers are assigned a NULL DrmPlane. The
DrmDisplayCompositor will scan its given layers for any that are missing planes.
In such a case, a DrmPlane is stolen from the last layer to receive a plane.
Then all layers in the DrmDisplayComposition that have no planes (including the
one stolen from) are composited synchronously using a GLWorkerCompositor and a
new layer is generated from the results. That layer is added to the
DrmDisplayComposition using the new import AddLayer function and the stolen
DrmPlane. DrmDisplayCompostior then continues as usual.

Change-Id: Ia6477c210c8f1307a4e537bec46889110d79ca18

1 files changed, 22 insertions, 0 deletions

diff --git a/drmdisplaycomposition.cpp b/drmdisplaycomposition.cpp
index cce1d56..21a9c2a 100644
--- a/drmdisplaycomposition.cpp
+++ b/drmdisplaycomposition.cpp
@@ -112,6 +112,28 @@ int DrmDisplayComposition::AddLayer(hwc_layer_1_t *layer, hwc_drm_bo_t *bo,
   return 0;
 }
 
+int DrmDisplayComposition::AddLayer(hwc_layer_1_t *layer, DrmCrtc *crtc,
+                                    DrmPlane *plane) {
+  if (layer->transform != 0)
+    return -EINVAL;
+
+  if (!validate_composition_type(DRM_COMPOSITION_TYPE_FRAME))
+    return -EINVAL;
+
+  hwc_drm_bo_t bo;
+  int ret = importer_->ImportBuffer(layer->handle, &bo);
+  if (ret) {
+    ALOGE("Failed to import handle of layer %d", ret);
+    return ret;
+  }
+
+  ret = AddLayer(layer, &bo, crtc, plane);
+  if (ret)
+    importer_->ReleaseBuffer(&bo);
+
+  return ret;
+}
+
 int DrmDisplayComposition::AddDpmsMode(uint32_t dpms_mode) {
   if (!validate_composition_type(DRM_COMPOSITION_TYPE_DPMS))
     return -EINVAL;