hwcomposer: Correctly synchronize reused buffers

Author: aleasto

hwcomposer/hwcomposer.cpp

@@ -206,6 +206,7 @@ static struct buffer *get_wl_buffer(struct waydroid_hwc_composer_device_1 *pdev,
     int ret = 0;
 
     buf = new struct buffer();
+    buf->timeline_fd = sw_sync_timeline_create();
     if (pdev->display->gtype == GRALLOC_GBM) {
         struct gralloc_handle_t *drm_handle = (struct gralloc_handle_t *)layer->handle;
         if (pdev->display->dmabuf) {
@@ -767,12 +768,8 @@ static int hwc_set(struct hwc_composer_device_1* dev,size_t numDisplays,
         if (fb_layer->compositionType != HWC_FRAMEBUFFER &&
             fb_layer->compositionType != HWC_SIDEBAND)
         {
-            int timeline_fd = sw_sync_timeline_create();
             /* To be signaled when the compositor releases the buffer */
-            fb_layer->releaseFenceFd = sw_sync_fence_create(timeline_fd, "wayland_release", 1);
-            buf->timeline_fd = timeline_fd;
-        } else {
-            buf->timeline_fd = -1;
+            fb_layer->releaseFenceFd = sw_sync_fence_create(buf->timeline_fd, "wayland_release", ++buf->sync_point);
         }
 
         struct wl_surface *surface = get_surface(pdev, fb_layer, window, pdev->use_subsurface);

hwcomposer/wayland-hwc.cpp

@@ -302,6 +302,7 @@ void snapshot_inactive_app_window(struct display *display, struct window *window
 
     struct buffer *old_buf = window->last_layer_buffer;
     struct buffer *new_buf = new struct buffer();
+    new_buf->timeline_fd = -1;
     // FIXME won't work as expected if there are multiple surfaces
     struct wl_surface *surface = window->surface;
 

hwcomposer/wayland-hwc.h

@@ -174,6 +174,7 @@ struct buffer {
     uint32_t hal_format;
 
     int timeline_fd;
+    int sync_point;
     bool isShm;
     void *shm_data;
     int size;