Set priority among various display devices

* When a non-WFD virtual display device (SSD/
screenrecord) is active along with
non-hybrid WFD solution(WFD faked on
external), give preference to non-hybrid WFD
device over non-WFD virtual display device.

* This is needed only in cases when WFD is
enabled via v4l2 rather than using VDS api's.

Change-Id: I63e53baa214bdcdac19430ca30b939cdd7416cbb

libhwcomposer/hwc_utils.cpp

@@ -188,6 +188,7 @@ void initContext(hwc_context_t *ctx)
     ctx->vstate.enable = false;
     ctx->vstate.fakevsync = false;
     ctx->mExtOrientation = 0;
+    ctx->numActiveDisplays = 1;
 
     //Right now hwc starts the service but anybody could do it, or it could be
     //independent process as well.
@@ -1910,6 +1911,32 @@ void reset_layer_prop(hwc_context_t* ctx, int dpy, int numAppLayers) {
     ctx->layerProp[dpy] = new LayerProp[numAppLayers];
 }
 
+/* Since we fake non-Hybrid WFD solution as external display, this
+ * function helps us in determining the priority between external
+ * (hdmi/non-Hybrid WFD display) and virtual display devices(SSD/
+ * screenrecord). This can be removed once wfd-client migrates to
+ * using virtual-display api's.
+ */
+bool canUseMDPforVirtualDisplay(hwc_context_t* ctx,
+                                const hwc_display_contents_1_t *list) {
+
+    /* We rely on the fact that for pure virtual display solution
+     * list->outbuf will be a non-NULL handle.
+     *
+     * If there are three active displays (which means there is one
+     * primary, one external and one virtual active display)
+     * we give mdss/mdp hw resources(pipes,smp,etc) for external
+     * display(hdmi/non-Hybrid WFD display) rather than for virtual
+     * display(SSD/screenrecord)
+     */
+
+    if(list->outbuf and (ctx->numActiveDisplays == HWC_NUM_DISPLAY_TYPES)) {
+        return false;
+    }
+
+    return true;
+}
+
 void BwcPM::setBwc(hwc_context_t *ctx, const hwc_rect_t& crop,
             const hwc_rect_t& dst, const int& transform,
             ovutils::eMdpFlags& mdpFlags) {