gl-renderer: call supports() automatically in create()

This means compositors don't need to call supports() manually and
create() will just return -1 in the failure case as before. This also
means we can deal with the case of eglGetProcAddress returning
non-NULL but not actually being available at runtime.

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

src/compositor-drm.c

@@ -1396,10 +1396,6 @@ drm_compositor_create_gl_renderer(struct drm_compositor *ec)
 {
 	EGLint format;
 
-	if (gl_renderer->supports(&ec->base, "gbm") < 0) {
-		return -1;
-	}
-
 	format = ec->format;
 	if (gl_renderer->create(&ec->base, EGL_PLATFORM_GBM_KHR, (void *) ec->gbm,
 			       gl_renderer->opaque_attribs, &format) < 0) {

src/compositor-fbdev.c

@@ -868,7 +868,8 @@ fbdev_compositor_create(struct wl_display *display, int *argc, char *argv[],
 			goto out_launcher;
 		}
 
-		if (gl_renderer->create(&compositor->base, 0, EGL_DEFAULT_DISPLAY,
+		if (gl_renderer->create(&compositor->base, NO_EGL_PLATFORM,
+					EGL_DEFAULT_DISPLAY,
 					gl_renderer->opaque_attribs,
 					NULL) < 0) {
 			weston_log("gl_renderer_create failed.\n");

src/compositor-wayland.c

@@ -1962,12 +1962,7 @@ wayland_compositor_create(struct wl_display *display, int use_pixman,
 	}
 
 	if (!c->use_pixman) {
-		if (gl_renderer->supports(&c->base, "wayland") < 0) {
+		if (gl_renderer->create(&c->base,
-			weston_log("No support for "
-			           "EGL_{KHR,EXT,MESA}_platform_wayland; "
-			           "falling back to pixman.\n");
-			c->use_pixman = 1;
-		} else if (gl_renderer->create(&c->base,
 					       EGL_PLATFORM_WAYLAND_KHR,
 					       c->parent.wl_display,
 					       gl_renderer->alpha_attribs,

src/compositor-x11.c

@@ -1492,9 +1492,6 @@ init_gl_renderer(struct x11_compositor *c)
 	if (!gl_renderer)
 		return -1;
 
-	if (gl_renderer->supports(&c->base, "x11") < 0)
-		return -1;
-
 	ret = gl_renderer->create(&c->base, EGL_PLATFORM_X11_KHR, (void *) c->dpy,
 				  gl_renderer->opaque_attribs, NULL);
 

src/gl-renderer.c

@@ -2240,6 +2240,21 @@ gl_renderer_supports(struct weston_compositor *ec,
 	return -1;
 }
 
+static const char *
+platform_to_extension(EGLenum platform)
+{
+	switch (platform) {
+	case EGL_PLATFORM_GBM_KHR:
+		return "gbm";
+	case EGL_PLATFORM_WAYLAND_KHR:
+		return "wayland";
+	case EGL_PLATFORM_X11_KHR:
+		return "x11";
+	default:
+		assert(0 && "bad EGL platform enum");
+	}
+}
+
 static int
 gl_renderer_create(struct weston_compositor *ec, EGLenum platform,
 	void *native_window, const EGLint *attribs,
@@ -2247,6 +2262,14 @@ gl_renderer_create(struct weston_compositor *ec, EGLenum platform,
 {
 	struct gl_renderer *gr;
 	EGLint major, minor;
+	int supports = 0;
+
+	if (platform) {
+		supports = gl_renderer_supports(
+			ec, platform_to_extension(platform));
+		if (supports < 0)
+			return -1;
+	}
 
 	gr = zalloc(sizeof *gr);
 	if (gr == NULL)
@@ -2261,26 +2284,34 @@ gl_renderer_create(struct weston_compositor *ec, EGLenum platform,
 	gr->base.surface_get_content_size =
 		gl_renderer_surface_get_content_size;
 	gr->base.surface_copy_content = gl_renderer_surface_copy_content;
+	gr->egl_display = NULL;
 
 #ifdef EGL_EXT_platform_base
+	/* the platform extension is supported */
+	if (supports) {
 		if (!get_platform_display) {
-		get_platform_display =
+			get_platform_display = (void *) eglGetProcAddress(
-			(void *) eglGetProcAddress("eglGetPlatformDisplayEXT");
+					"eglGetPlatformDisplayEXT");
 		}
 
+		/* also wrap this in the supports check because
+		 * eglGetProcAddress can return non-NULL and still not
+		 * support the feature at runtime, so ensure the
+		 * appropriate extension checks have been done. */
 		if (get_platform_display && platform) {
-		gr->egl_display =
+			gr->egl_display = get_platform_display(platform,
-			get_platform_display(platform, native_window,
+							       native_window,
 							       NULL);
-	} else {
+		}
+	}
 #endif
+
+	if (!gr->egl_display) {
 		weston_log("warning: either no EGL_EXT_platform_base "
 			   "support or specific platform support; "
 			   "falling back to eglGetDisplay.\n");
 		gr->egl_display = eglGetDisplay(native_window);
-#ifdef EGL_EXT_platform_base
 	}
-#endif
 
 	if (gr->egl_display == EGL_NO_DISPLAY) {
 		weston_log("failed to create display\n");
@@ -2493,7 +2524,6 @@ WL_EXPORT struct gl_renderer_interface gl_renderer_interface = {
 	.opaque_attribs = gl_renderer_opaque_attribs,
 	.alpha_attribs = gl_renderer_alpha_attribs,
 
-	.supports = gl_renderer_supports,
 	.create = gl_renderer_create,
 	.display = gl_renderer_display,
 	.output_create = gl_renderer_output_create,

src/gl-renderer.h

@@ -53,6 +53,8 @@ typedef intptr_t EGLNativeWindowType;
 #define EGL_PLATFORM_X11_KHR 0x31D5
 #endif
 
+#define NO_EGL_PLATFORM 0
+
 enum gl_renderer_border_side {
 	GL_RENDERER_BORDER_TOP = 0,
 	GL_RENDERER_BORDER_LEFT = 1,
@@ -64,9 +66,6 @@ struct gl_renderer_interface {
 	const EGLint *opaque_attribs;
 	const EGLint *alpha_attribs;
 
-	int (*supports)(struct weston_compositor *ec,
-			const char *extension_suffix);
-
 	int (*create)(struct weston_compositor *ec,
 		      EGLenum platform,
 		      void *native_window,