drm_hwcomposer: add scene flattening
Flattening of a scene is triggered if it doesn't change for a while.
As of now there is a separate thread which triggers flattening if the
scene did not change in last 60 vsyncs.
There are two options for flattening a scene:
* Serial, by using a writeback connector attached to the same crtc as
the one driving the display. This happens only if possible_clones
mask reports that the display encoder and writeback encoder could
work simultaneously.
The steps for achieving this are:
1. Build a commit that enables writeback connector, we don't need to
build a commit that contains the entire active_composition, just
set the writeback specific properties a let the kernel duplicate
the rest of the state.
2. Commit and wait for writeback_fence to fire.
3. Setup a composition with just one plane enabled.
4. Apply the composition if a new one has not been applied meanwhile.
* Concurrent, by comitting the scene to a new unused crtc (state !=
DRM_MODE_CONNECTED) and getting the result back through a writeback
connector.
The steps for achieving this are:
1. Copy layers from active composition.
2. Plan layers of copy on the unused crtc. This is realized by using a
newly created DrmDisplayCompositor object.
3. Commit copy to the unsed crtc and get the result as a drmhwclayer.
4. Setup a composition with just one plane enabled. Re-importing the
buffers might be needed since we might have been using a different
dri node.
5. Apply the composition if a new one has not been applied while doing
the flattening
Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
diff --git a/drmdevice.h b/drmdevice.h
index 671cab6..491a9b0 100644
--- a/drmdevice.h
+++ b/drmdevice.h
@@ -58,6 +58,7 @@
DrmConnector *GetConnectorForDisplay(int display) const;
DrmConnector *GetWritebackConnectorForDisplay(int display) const;
+ DrmConnector *AvailableWritebackConnector(int display) const;
DrmCrtc *GetCrtcForDisplay(int display) const;
DrmPlane *GetPlane(uint32_t id) const;
DrmEventListener *event_listener();