hw/xwayland/xwayland-glamor-eglstream.c

@@ -437,8 +437,8 @@ xwl_eglstream_consumer_ready_callback(void *data,
     DebugF("eglstream: win %d completes eglstream for pixmap %p, congrats!\n",
            pending->window->drawable.id, pending->pixmap);
 
-    xwl_eglstream_window_set_pending(pending->window, NULL);
 out:
+    xwl_eglstream_window_set_pending(pending->window, NULL);
     xorg_list_del(&pending->link);
     free(pending);
 }
@@ -939,4 +939,5 @@ xwl_glamor_init_eglstream(struct xwl_screen *xwl_screen)
     xwl_screen->eglstream_backend.post_damage = xwl_glamor_eglstream_post_damage;
     xwl_screen->eglstream_backend.allow_commits = xwl_glamor_eglstream_allow_commits;
     xwl_screen->eglstream_backend.is_available = TRUE;
+    xwl_screen->eglstream_backend.backend_flags = XWL_EGL_BACKEND_NO_FLAG;
 }

hw/xwayland/xwayland-glamor-gbm.c

@@ -1116,4 +1116,7 @@ xwl_glamor_init_gbm(struct xwl_screen *xwl_screen)
     xwl_screen->gbm_backend.init_screen = xwl_glamor_gbm_init_screen;
     xwl_screen->gbm_backend.get_wl_buffer_for_pixmap = xwl_glamor_gbm_get_wl_buffer_for_pixmap;
     xwl_screen->gbm_backend.is_available = TRUE;
+    xwl_screen->gbm_backend.backend_flags = XWL_EGL_BACKEND_HAS_PRESENT_FLIP |
+                                            XWL_EGL_BACKEND_NEEDS_BUFFER_FLUSH |
+                                            XWL_EGL_BACKEND_NEEDS_N_BUFFERING;
 }

hw/xwayland/xwayland-glamor.c

@@ -176,6 +176,37 @@ glamor_egl_fd_name_from_pixmap(ScreenPtr screen,
     return 0;
 }
 
+Bool
+xwl_glamor_has_present_flip(struct xwl_screen *xwl_screen)
+{
+    if (!xwl_screen->glamor || !xwl_screen->egl_backend)
+        return FALSE;
+
+    return (xwl_screen->egl_backend->backend_flags &
+                XWL_EGL_BACKEND_HAS_PRESENT_FLIP);
+}
+
+Bool
+xwl_glamor_needs_buffer_flush(struct xwl_screen *xwl_screen)
+{
+    if (!xwl_screen->glamor || !xwl_screen->egl_backend)
+        return FALSE;
+
+    return (xwl_screen->egl_backend->backend_flags &
+                XWL_EGL_BACKEND_NEEDS_BUFFER_FLUSH);
+}
+
+Bool
+xwl_glamor_needs_n_buffering(struct xwl_screen *xwl_screen)
+{
+    /* wl_shm benefits from n-buffering */
+    if (!xwl_screen->glamor || !xwl_screen->egl_backend)
+        return TRUE;
+
+    return (xwl_screen->egl_backend->backend_flags &
+                XWL_EGL_BACKEND_NEEDS_N_BUFFERING);
+}
+
 void
 xwl_glamor_init_backends(struct xwl_screen *xwl_screen, Bool use_eglstream)
 {

hw/xwayland/xwayland-glamor.h

@@ -32,10 +32,20 @@
 
 #include "xwayland-types.h"
 
+typedef enum _xwl_egl_backend_flags {
+    XWL_EGL_BACKEND_NO_FLAG = 0,
+    XWL_EGL_BACKEND_HAS_PRESENT_FLIP = (1 << 0),
+    XWL_EGL_BACKEND_NEEDS_BUFFER_FLUSH = (1 << 1),
+    XWL_EGL_BACKEND_NEEDS_N_BUFFERING = (1 << 2),
+} xwl_egl_backend_flags;
+
 struct xwl_egl_backend {
     /* Set by the backend if available */
     Bool is_available;
 
+    /* Features and requirements set by the backend */
+    xwl_egl_backend_flags backend_flags;
+
     /* Called once for each interface in the global registry. Backends
      * should use this to bind to any wayland interfaces they need.
      */
@@ -109,6 +119,10 @@ void xwl_glamor_post_damage(struct xwl_window *xwl_window,
                             PixmapPtr pixmap, RegionPtr region);
 Bool xwl_glamor_allow_commits(struct xwl_window *xwl_window);
 void xwl_glamor_egl_make_current(struct xwl_screen *xwl_screen);
+Bool xwl_glamor_has_present_flip(struct xwl_screen *xwl_screen);
+Bool xwl_glamor_needs_buffer_flush(struct xwl_screen *xwl_screen);
+Bool xwl_glamor_needs_n_buffering(struct xwl_screen *xwl_screen);
+
 
 #ifdef XV
 /* glamor Xv Adaptor */

hw/xwayland/xwayland-present.c

@@ -540,10 +540,7 @@ xwl_present_init(ScreenPtr screen)
 {
     struct xwl_screen *xwl_screen = xwl_screen_get(screen);
 
-    /*
-     * doesn't work with the EGLStream backend.
-     */
-    if (xwl_screen->egl_backend == &xwl_screen->eglstream_backend)
+    if (!xwl_glamor_has_present_flip(xwl_screen))
         return FALSE;
 
     if (!dixRegisterPrivateKey(&xwl_present_window_private_key, PRIVATE_WINDOW, 0))

hw/xwayland/xwayland-screen.c

@@ -330,10 +330,8 @@ xwl_screen_post_damage(struct xwl_screen *xwl_screen)
         return;
 
 #ifdef XWL_HAS_GLAMOR
-    if (xwl_screen->glamor &&
-        xwl_screen->egl_backend == &xwl_screen->gbm_backend) {
+    if (xwl_glamor_needs_buffer_flush(xwl_screen))
         glamor_block_handler(xwl_screen->screen);
-    }
 #endif
 
     xorg_list_for_each_entry_safe(xwl_window, next_xwl_window,

hw/xwayland/xwayland-window-buffers.c

@@ -279,6 +279,11 @@ xwl_window_buffers_get_pixmap(struct xwl_window *xwl_window,
 
     window_pixmap = (*xwl_screen->screen->GetWindowPixmap) (xwl_window->window);
 
+#ifdef XWL_HAS_GLAMOR
+    if (!xwl_glamor_needs_n_buffering(xwl_screen))
+        return window_pixmap;
+#endif /* XWL_HAS_GLAMOR */
+
     xwl_window_buffer = xwl_window_buffer_get_available(xwl_window);
     if (!xwl_window_buffer)
         return window_pixmap;