kms: Use a dummy surface instead of the surfaceless extension

The surfaceless extension that Mesa advertises has been renamed to
EGL_KHR_surfaceless_context instead of a separate extension for the
GLES, GLES2 and GL APIs and the new extension has been ratified by
Khronos. Therefore the KMS backend no longer runs against Mesa master.
We could just rename the extension we check for, however Weston (the
sample Wayland compositor) has switched to just creating a dummy GBM
surface and not using the surfaceless extension at all. We should
probably do the same thing.

Using the surfaceless extension could be a good idea but we don't
really need to rely on it for KMS and we would want to do it for all
EGL backends, not just the KMS backend.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit d4f22f8cb013d417c99ba03924538924191c2fe6)

cogl/winsys/cogl-winsys-egl-feature-functions.h

@@ -88,18 +88,3 @@ COGL_WINSYS_FEATURE_FUNCTION (EGLBoolean, eglUnbindWaylandDisplay,
                                struct wl_display *wayland_display))
 COGL_WINSYS_FEATURE_END ()
 #endif
-COGL_WINSYS_FEATURE_BEGIN (surfaceless_opengl,
-                           "KHR\0",
-                           "surfaceless_opengl\0",
-                           COGL_EGL_WINSYS_FEATURE_SURFACELESS_OPENGL)
-COGL_WINSYS_FEATURE_END ()
-COGL_WINSYS_FEATURE_BEGIN (surfaceless_gles1,
-                           "KHR\0",
-                           "surfaceless_gles1\0",
-                           COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES1)
-COGL_WINSYS_FEATURE_END ()
-COGL_WINSYS_FEATURE_BEGIN (surfaceless_gles2,
-                           "KHR\0",
-                           "surfaceless_gles2\0",
-                           COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES2)
-COGL_WINSYS_FEATURE_END ()

cogl/winsys/cogl-winsys-egl-kms.c

@@ -79,6 +79,7 @@ typedef struct _CoglDisplayKMS
   int width, height;
   CoglBool pending_set_crtc;
   CoglBool pending_swap_notify;
+  struct gbm_surface *dummy_gbm_surface;
 } CoglDisplayKMS;
 
 typedef struct _CoglFlipKMS
@@ -388,8 +389,6 @@ _cogl_winsys_egl_display_setup (CoglDisplay *display,
   CoglDisplayKMS *kms_display;
   CoglRendererEGL *egl_renderer = display->renderer->winsys;
   CoglRendererKMS *kms_renderer = egl_renderer->platform;
-  CoglEGLWinsysFeature surfaceless_feature = 0;
-  const char *surfaceless_feature_name = "";
   drmModeRes *resources;
   CoglOutputKMS *output0, *output1;
   CoglBool mirror;
@@ -397,33 +396,6 @@ _cogl_winsys_egl_display_setup (CoglDisplay *display,
   kms_display = g_slice_new0 (CoglDisplayKMS);
   egl_display->platform = kms_display;
 
-  switch (display->renderer->driver)
-    {
-    case COGL_DRIVER_GL:
-      surfaceless_feature = COGL_EGL_WINSYS_FEATURE_SURFACELESS_OPENGL;
-      surfaceless_feature_name = "opengl";
-      break;
-    case COGL_DRIVER_GLES1:
-      surfaceless_feature = COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES1;
-      surfaceless_feature_name = "gles1";
-      break;
-    case COGL_DRIVER_GLES2:
-      surfaceless_feature = COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES2;
-      surfaceless_feature_name = "gles2";
-      break;
-    case COGL_DRIVER_ANY:
-      g_return_val_if_reached (FALSE);
-    }
-
-  if (!(egl_renderer->private_features & surfaceless_feature))
-    {
-      g_set_error (error, COGL_WINSYS_ERROR,
-                   COGL_WINSYS_ERROR_INIT,
-                   "EGL_KHR_surfaceless_%s extension not available",
-                   surfaceless_feature_name);
-      return FALSE;
-    }
-
   resources = drmModeGetResources (kms_renderer->fd);
   if (!resources)
     {
@@ -538,10 +510,39 @@ _cogl_winsys_egl_context_created (CoglDisplay *display,
                                   GError **error)
 {
   CoglDisplayEGL *egl_display = display->winsys;
+  CoglDisplayKMS *kms_display = egl_display->platform;
+  CoglRenderer *renderer = display->renderer;
+  CoglRendererEGL *egl_renderer = renderer->winsys;
+  CoglRendererKMS *kms_renderer = egl_renderer->platform;
+
+  kms_display->dummy_gbm_surface = gbm_surface_create (kms_renderer->gbm,
+                                                       16, 16,
+                                                       GBM_FORMAT_XRGB8888,
+                                                       GBM_BO_USE_RENDERING);
+  if (!kms_display->dummy_gbm_surface)
+    {
+      g_set_error (error, COGL_WINSYS_ERROR,
+                   COGL_WINSYS_ERROR_CREATE_CONTEXT,
+                   "Failed to create dummy GBM surface");
+      return FALSE;
+    }
+
+  egl_display->dummy_surface =
+    eglCreateWindowSurface (egl_renderer->edpy,
+                            egl_display->egl_config,
+                            (NativeWindowType) kms_display->dummy_gbm_surface,
+                            NULL);
+  if (egl_display->dummy_surface == EGL_NO_SURFACE)
+    {
+      g_set_error (error, COGL_WINSYS_ERROR,
+                   COGL_WINSYS_ERROR_CREATE_CONTEXT,
+                   "Failed to create dummy EGL surface");
+      return FALSE;
+    }
 
   if (!_cogl_winsys_egl_make_current (display,
-                                      EGL_NO_SURFACE,
+                                      egl_display->dummy_surface,
-                                      EGL_NO_SURFACE,
+                                      egl_display->dummy_surface,
                                       egl_display->egl_context))
     {
       g_set_error (error, COGL_WINSYS_ERROR,
@@ -556,6 +557,22 @@ _cogl_winsys_egl_context_created (CoglDisplay *display,
 static void
 _cogl_winsys_egl_cleanup_context (CoglDisplay *display)
 {
+  CoglDisplayEGL *egl_display = display->winsys;
+  CoglDisplayKMS *kms_display = egl_display->platform;
+  CoglRenderer *renderer = display->renderer;
+  CoglRendererEGL *egl_renderer = renderer->winsys;
+
+  if (egl_display->dummy_surface != EGL_NO_SURFACE)
+    {
+      eglDestroySurface (egl_renderer->edpy, egl_display->dummy_surface);
+      egl_display->dummy_surface = EGL_NO_SURFACE;
+    }
+
+  if (kms_display->dummy_gbm_surface != NULL)
+    {
+      gbm_surface_destroy (kms_display->dummy_gbm_surface);
+      kms_display->dummy_gbm_surface = NULL;
+    }
 }
 
 static void

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

@@ -68,10 +68,7 @@ typedef enum _CoglEGLWinsysFeature
 {
   COGL_EGL_WINSYS_FEATURE_SWAP_REGION                   =1L<<0,
   COGL_EGL_WINSYS_FEATURE_EGL_IMAGE_FROM_X11_PIXMAP     =1L<<1,
-  COGL_EGL_WINSYS_FEATURE_EGL_IMAGE_FROM_WAYLAND_BUFFER =1L<<2,
+  COGL_EGL_WINSYS_FEATURE_EGL_IMAGE_FROM_WAYLAND_BUFFER =1L<<2
-  COGL_EGL_WINSYS_FEATURE_SURFACELESS_OPENGL            =1L<<3,
-  COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES1             =1L<<4,
-  COGL_EGL_WINSYS_FEATURE_SURFACELESS_GLES2             =1L<<5
 } CoglEGLWinsysFeature;
 
 typedef struct _CoglRendererEGL