cogl/renderer: Add 'is_dma_buf_supported()' vfunc

Returns TRUE if the active renderer backend can allocate DMA buffers.
This is the case hardware accelerated GBM backends, but FALSE for
surfaceless (i.e. no render node) and EGLDevice (legacy NVIDIA paths).
While software based gbm devices can allocate DMA buffers, we don't want
to allocate them for offscreen rendering, as we really only use these
for inter process transfers, and as buffers allocated for scanout
doesn't use the relevant API, making it return FALSE for these solves
that.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1939>

cogl/cogl/cogl-renderer.c

@@ -773,6 +773,17 @@ cogl_renderer_create_dma_buf (CoglRenderer  *renderer,
   return NULL;
 }
 
+gboolean
+cogl_renderer_is_dma_buf_supported (CoglRenderer *renderer)
+{
+  const CoglWinsysVtable *winsys = _cogl_renderer_get_winsys (renderer);
+
+  if (winsys->renderer_is_dma_buf_supported)
+    return winsys->renderer_is_dma_buf_supported (renderer);
+  else
+    return FALSE;
+}
+
 void
 cogl_renderer_bind_api (CoglRenderer *renderer)
 {

cogl/cogl/cogl-renderer.h

@@ -419,6 +419,16 @@ cogl_renderer_create_dma_buf (CoglRenderer  *renderer,
                               int            height,
                               GError       **error);
 
+
+/**
+ * cogl_renderer_is_dma_buf_supported: (skip)
+ * @renderer: A #CoglRenderer
+ *
+ * Returns: %TRUE if DMA buffers can be allocated
+ */
+COGL_EXPORT gboolean
+cogl_renderer_is_dma_buf_supported (CoglRenderer *renderer);
+
 /**
  * cogl_renderer_bind_api: (skip)
  */

cogl/cogl/winsys/cogl-winsys-private.h

@@ -73,11 +73,12 @@ typedef struct _CoglWinsysVtable
 
   GCallback
   (*renderer_get_proc_address) (CoglRenderer *renderer,
-                                const char *name,
-                                gboolean in_core);
+                                const char   *name,
+                                gboolean      in_core);
 
   gboolean
-  (*renderer_connect) (CoglRenderer *renderer, GError **error);
+  (*renderer_connect) (CoglRenderer *renderer,
+                       GError      **error);
 
   void
   (*renderer_disconnect) (CoglRenderer *renderer);
@@ -86,7 +87,8 @@ typedef struct _CoglWinsysVtable
   (*renderer_outputs_changed) (CoglRenderer *renderer);
 
   gboolean
-  (*display_setup) (CoglDisplay *display, GError **error);
+  (*display_setup) (CoglDisplay *display,
+                    GError     **error);
 
   void
   (*display_destroy) (CoglDisplay *display);
@@ -97,11 +99,15 @@ typedef struct _CoglWinsysVtable
                               int            height,
                               GError       **error);
 
+  gboolean
+  (*renderer_is_dma_buf_supported) (CoglRenderer *renderer);
+
   void
   (*renderer_bind_api) (CoglRenderer *renderer);
 
   gboolean
-  (*context_init) (CoglContext *context, GError **error);
+  (*context_init) (CoglContext *context,
+                   GError     **error);
 
   void
   (*context_deinit) (CoglContext *context);
@@ -115,15 +121,15 @@ typedef struct _CoglWinsysVtable
   (*texture_pixmap_x11_free) (CoglTexturePixmapX11 *tex_pixmap);
 
   gboolean
-  (*texture_pixmap_x11_update) (CoglTexturePixmapX11 *tex_pixmap,
+  (*texture_pixmap_x11_update) (CoglTexturePixmapX11       *tex_pixmap,
                                 CoglTexturePixmapStereoMode stereo_mode,
-                                gboolean needs_mipmap);
+                                gboolean                    needs_mipmap);
 
   void
   (*texture_pixmap_x11_damage_notify) (CoglTexturePixmapX11 *tex_pixmap);
 
   CoglTexture *
-  (*texture_pixmap_x11_get_texture) (CoglTexturePixmapX11 *tex_pixmap,
+  (*texture_pixmap_x11_get_texture) (CoglTexturePixmapX11       *tex_pixmap,
                                      CoglTexturePixmapStereoMode stereo_mode);
 #endif
 
@@ -131,10 +137,12 @@ typedef struct _CoglWinsysVtable
   (*fence_add) (CoglContext *ctx);
 
   gboolean
-  (*fence_is_complete) (CoglContext *ctx, void *fence);
+  (*fence_is_complete) (CoglContext *ctx,
+                        void        *fence);
 
   void
-  (*fence_destroy) (CoglContext *ctx, void *fence);
+  (*fence_destroy) (CoglContext *ctx,
+                    void        *fence);
 
 } CoglWinsysVtable;
 

src/backends/native/meta-renderer-native.c

@@ -970,6 +970,27 @@ meta_renderer_native_create_dma_buf (CoglRenderer  *cogl_renderer,
   return NULL;
 }
 
+static gboolean
+meta_renderer_native_is_dma_buf_supported (CoglRenderer *cogl_renderer)
+{
+  CoglRendererEGL *cogl_renderer_egl = cogl_renderer->winsys;
+  MetaRendererNativeGpuData *renderer_gpu_data = cogl_renderer_egl->platform;
+  MetaRenderDevice *render_device = renderer_gpu_data->render_device;
+
+  switch (renderer_gpu_data->mode)
+    {
+    case META_RENDERER_NATIVE_MODE_GBM:
+      return meta_render_device_is_hardware_accelerated (render_device);
+    case META_RENDERER_NATIVE_MODE_SURFACELESS:
+#ifdef HAVE_EGL_DEVICE
+    case META_RENDERER_NATIVE_MODE_EGL_DEVICE:
+#endif
+      return FALSE;
+    }
+
+  g_assert_not_reached ();
+}
+
 static gboolean
 meta_renderer_native_init_egl_context (CoglContext *cogl_context,
                                        GError     **error)
@@ -1114,6 +1135,8 @@ get_native_cogl_winsys_vtable (CoglRenderer *cogl_renderer)
       vtable.renderer_connect = meta_renderer_native_connect;
       vtable.renderer_disconnect = meta_renderer_native_disconnect;
       vtable.renderer_create_dma_buf = meta_renderer_native_create_dma_buf;
+      vtable.renderer_is_dma_buf_supported =
+        meta_renderer_native_is_dma_buf_supported;
 
       vtable_inited = TRUE;
     }