[cogl/cogl-1.18] kms-winsys: Defer setting new surfaces until swap buffers

[Robert Bragg <rbragg src gnome org>]

commit 200c4032ac60112a7c27d14ad3ba1c768e6b970c
Author: Rui Matos <tiagomatos gmail com>
Date:   Wed Feb 18 15:24:14 2015 +0100

    kms-winsys: Defer setting new surfaces until swap buffers
    
    We can't just destroy and replace the EGL and gbm surfaces while
    they are still in use i.e. while there is a pending flip. In fact, in
    that case, we were calling gbm_surface_destroy() on a surface that
    still had the front buffer locked and then, on the flip handler,
    gbm_surface_release_buffer() for a buffer that didn't belong to the
    new surface.
    
    Instead, we still allocate new surfaces when requested but they only
    replace the old ones on the next swap buffers when we're sure that the
    previous flip has been handled and buffers properly released.

 cogl/winsys/cogl-winsys-egl-kms.c |   34 ++++++++++++++++++++++++++--------
 1 files changed, 26 insertions(+), 8 deletions(-)
---
diff --git a/cogl/winsys/cogl-winsys-egl-kms.c b/cogl/winsys/cogl-winsys-egl-kms.c
index 86f57c0..dbedb0c 100644
--- a/cogl/winsys/cogl-winsys-egl-kms.c
+++ b/cogl/winsys/cogl-winsys-egl-kms.c
@@ -110,6 +110,9 @@ typedef struct _CoglOnscreenKMS
   struct gbm_bo *current_bo;
   struct gbm_bo *next_bo;
   CoglBool pending_swap_notify;
+
+  EGLSurface *pending_egl_surface;
+  struct gbm_surface *pending_surface;
 } CoglOnscreenKMS;
 
 static const char device_name[] = "/dev/dri/card0";
@@ -868,10 +871,27 @@ _cogl_winsys_onscreen_swap_buffers_with_damage (CoglOnscreen *onscreen,
   while (kms_onscreen->next_fb_id != 0)
     handle_drm_event (kms_renderer);
 
+  if (kms_onscreen->pending_egl_surface)
+    {
+      eglDestroySurface (egl_renderer->edpy, egl_onscreen->egl_surface);
+      egl_onscreen->egl_surface = kms_onscreen->pending_egl_surface;
+      kms_onscreen->pending_egl_surface = NULL;
+
+      _cogl_framebuffer_winsys_update_size (COGL_FRAMEBUFFER (kms_display->onscreen),
+                                            kms_display->width, kms_display->height);
+      context->current_draw_buffer_changes |= COGL_FRAMEBUFFER_STATE_BIND;
+    }
   parent_vtable->onscreen_swap_buffers_with_damage (onscreen,
                                                     rectangles,
                                                     n_rectangles);
 
+  if (kms_onscreen->pending_surface)
+    {
+      free_current_bo (onscreen);
+      gbm_surface_destroy (kms_onscreen->surface);
+      kms_onscreen->surface = kms_onscreen->pending_surface;
+      kms_onscreen->pending_surface = NULL;
+    }
   /* Now we need to set the CRTC to whatever is the front buffer */
   kms_onscreen->next_bo = gbm_surface_lock_front_buffer (kms_onscreen->surface);
 
@@ -1177,7 +1197,6 @@ cogl_kms_display_set_layout (CoglDisplay *display,
        height != kms_display->height) &&
       kms_display->onscreen)
     {
-      CoglContext *context = COGL_FRAMEBUFFER (kms_display->onscreen)->context;
       CoglOnscreenEGL *egl_onscreen = kms_display->onscreen->winsys;
       CoglOnscreenKMS *kms_onscreen = egl_onscreen->platform;
       struct gbm_surface *new_surface;
@@ -1213,14 +1232,13 @@ cogl_kms_display_set_layout (CoglDisplay *display,
           return FALSE;
         }
 
-      eglDestroySurface (egl_renderer->edpy, egl_onscreen->egl_surface);
-      gbm_surface_destroy (kms_onscreen->surface);
-
-      kms_onscreen->surface = new_surface;
-      egl_onscreen->egl_surface = new_egl_surface;
+      if (kms_onscreen->pending_egl_surface)
+        eglDestroySurface (egl_renderer->edpy, kms_onscreen->pending_egl_surface);
+      if (kms_onscreen->pending_surface)
+        gbm_surface_destroy (kms_onscreen->pending_surface);
 
-      _cogl_framebuffer_winsys_update_size (COGL_FRAMEBUFFER (kms_display->onscreen), width, height);
-      context->current_draw_buffer_changes |= COGL_FRAMEBUFFER_STATE_BIND;
+      kms_onscreen->pending_surface = new_surface;
+      kms_onscreen->pending_egl_surface = new_egl_surface;
     }
 
   kms_display->width = width;