rpi: Dispmanx elements as planes, completion callback

Dispmanx elements are like hardware overlays. Assign one weston_surface
to each overlay created, and the VideoCore will composite it on screen.
The maximum number of elements is configurable via the command line.
Specifying zero will disable the overlays (planes/elements) altogether,
and use only GLESv2 compositing.

You need an up-to-date Raspberry Pi firmware for:
- vc_dispmanx_resource_create(), that will also take stride. Otherwise
  surfaces ending up in elements may show up as corrupted.
- off-line compositing support. The on-line compositing of elements
  cannot handle too many elements. Look for the comments around
  DEFAULT_MAX_PLANES in the code.

Elements must be double-buffered to avoid tearing. Therefore two buffers
(Dispmanx resources) are allocated for each element. A command line
option is added to allow single-buffering instead to save memory, with
the risk of tearing.

The page flip timer is replaced with the Dispmanx update completion
callback. The callback is executed in a separate thread, therefore a
pipe is set up to integrate properly with Weston core.

If not disabled, usually all surfaces are assigned into planes, and
nothing is composited in GLESv2. Planes do not support surface
transformations though, so compositing will automatically switch the
necessary surfaces to GLESv2 compositing as needed. Switching between
GLESv2 and elements may cause transient visual glitches and jerks.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

src/rpi-bcm-stubs.h

@@ -63,6 +63,14 @@ typedef enum {
 	VC_IMAGE_ROT0,
 } VC_IMAGE_TRANSFORM_T;
 
+typedef enum
+{
+	VC_IMAGE_MIN = 0,
+	/* these are not the right values: */
+	VC_IMAGE_ARGB8888,
+	VC_IMAGE_XRGB8888,
+} VC_IMAGE_TYPE_T;
+
 /* from /opt/vc/include/interface/vmcs_host/vc_dispmanx_types.h */
 
 typedef uint32_t DISPMANX_DISPLAY_HANDLE_T;
@@ -107,6 +115,9 @@ typedef struct {
 	uint32_t dummy;
 } DISPMANX_CLAMP_T;
 
+typedef void (*DISPMANX_CALLBACK_FUNC_T)(DISPMANX_UPDATE_HANDLE_T u,
+					 void *arg);
+
 /* from /opt/vc/include/interface/vmcs_host/vc_dispmanx.h */
 
 static inline int
@@ -120,10 +131,45 @@ vc_dispmanx_rect_set(VC_RECT_T *rect, uint32_t x_offset, uint32_t y_offset,
 	return 0;
 }
 
+static inline DISPMANX_RESOURCE_HANDLE_T
+vc_dispmanx_resource_create(VC_IMAGE_TYPE_T type, uint32_t width,
+			    uint32_t height, uint32_t *native_image_handle)
+{
+	return DISPMANX_NO_HANDLE;
+}
+
+static inline int
+vc_dispmanx_resource_write_data(DISPMANX_RESOURCE_HANDLE_T res,
+				VC_IMAGE_TYPE_T src_type,
+				int src_pitch,
+				void *src_address,
+				const VC_RECT_T *rect)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_resource_write_data_rect(DISPMANX_RESOURCE_HANDLE_T handle,
+				     VC_IMAGE_TYPE_T src_type,
+				     int src_pitch,
+				     void *src_address,
+				     const VC_RECT_T *src_rect,
+				     uint32_t dst_x,
+				     uint32_t dst_y)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_resource_delete(DISPMANX_RESOURCE_HANDLE_T res)
+{
+	return -1;
+}
+
 static inline DISPMANX_DISPLAY_HANDLE_T
 vc_dispmanx_display_open(uint32_t device)
 {
-	return -1;
+	return DISPMANX_NO_HANDLE;
 }
 
 static inline int
@@ -142,7 +188,7 @@ vc_dispmanx_display_get_info(DISPMANX_DISPLAY_HANDLE_T display,
 static inline DISPMANX_UPDATE_HANDLE_T
 vc_dispmanx_update_start(int32_t priority)
 {
-	return -1;
+	return DISPMANX_NO_HANDLE;
 }
 
 static inline DISPMANX_ELEMENT_HANDLE_T
@@ -156,6 +202,22 @@ vc_dispmanx_element_add(DISPMANX_UPDATE_HANDLE_T update,
 			VC_DISPMANX_ALPHA_T *alpha,
 			DISPMANX_CLAMP_T *clamp,
 			DISPMANX_TRANSFORM_T transform)
+{
+	return DISPMANX_NO_HANDLE;
+}
+
+static inline int
+vc_dispmanx_element_change_source(DISPMANX_UPDATE_HANDLE_T update,
+				  DISPMANX_ELEMENT_HANDLE_T element,
+				  DISPMANX_RESOURCE_HANDLE_T src)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_element_modified(DISPMANX_UPDATE_HANDLE_T update,
+			     DISPMANX_ELEMENT_HANDLE_T element,
+			     const VC_RECT_T *rect)
 {
 	return -1;
 }
@@ -167,12 +229,33 @@ vc_dispmanx_element_remove(DISPMANX_UPDATE_HANDLE_T update,
 	return -1;
 }
 
+static inline int
+vc_dispmanx_update_submit(DISPMANX_UPDATE_HANDLE_T update,
+			  DISPMANX_CALLBACK_FUNC_T cb_func, void *cb_arg)
+{
+	return -1;
+}
+
 static inline int
 vc_dispmanx_update_submit_sync(DISPMANX_UPDATE_HANDLE_T update)
 {
 	return -1;
 }
 
+static inline int
+vc_dispmanx_element_change_attributes(DISPMANX_UPDATE_HANDLE_T update,
+				      DISPMANX_ELEMENT_HANDLE_T element,
+				      uint32_t change_flags,
+				      int32_t layer,
+				      uint8_t opacity,
+				      const VC_RECT_T *dest_rect,
+				      const VC_RECT_T *src_rect,
+				      DISPMANX_RESOURCE_HANDLE_T mask,
+				      VC_IMAGE_TRANSFORM_T transform)
+{
+	return -1;
+}
+
 /* from /opt/vc/include/EGL/eglplatform.h */
 
 typedef struct {