drm/exynos: disallow fbdev initialization if no device is connected

This patch adds explicit check if there is a connector with
connected status before fbdev initialization. It prevents creation
of default fbdev 1024x768 which is unusable on panels with bigger resolutions.
Signed-off-by: NAndrzej Hajda <a.hajda@samsung.com>
Signed-off-by: NInki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -237,6 +237,24 @@ static struct drm_fb_helper_funcs exynos_drm_fb_helper_funcs = {
 	.fb_probe =	exynos_drm_fbdev_create,
 };
 
+bool exynos_drm_fbdev_is_anything_connected(struct drm_device *dev)
+{
+	struct drm_connector *connector;
+	bool ret = false;
+
+	mutex_lock(&dev->mode_config.mutex);
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (connector->status != connector_status_connected)
+			continue;
+
+		ret = true;
+		break;
+	}
+	mutex_unlock(&dev->mode_config.mutex);
+
+	return ret;
+}
+
 int exynos_drm_fbdev_init(struct drm_device *dev)
 {
 	struct exynos_drm_fbdev *fbdev;
@@ -248,6 +266,9 @@ int exynos_drm_fbdev_init(struct drm_device *dev)
 	if (!dev->mode_config.num_crtc || !dev->mode_config.num_connector)
 		return 0;
 
+	if (!exynos_drm_fbdev_is_anything_connected(dev))
+		return 0;
+
 	fbdev = kzalloc(sizeof(*fbdev), GFP_KERNEL);
 	if (!fbdev)
 		return -ENOMEM;