drm/msm/dsi: check msm_dsi and dsi pointers before use

Move null checks of pointer arguments to the beginning of the
modeset init function since they are referenced immediately
instead of after they have already been used.
Signed-off-by: Lloyd Atkinson <latkinso@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/dsi/dsi.c

@@ -196,7 +196,7 @@ int msm_dsi_modeset_init(struct msm_dsi *msm_dsi, struct drm_device *dev,
 	struct drm_bridge *ext_bridge;
 	int ret;
 
-	if (WARN_ON(!encoder))
+	if (WARN_ON(!encoder) || WARN_ON(!msm_dsi) || WARN_ON(!dev))
 		return -EINVAL;
 
 	msm_dsi->dev = dev;
@@ -245,19 +245,17 @@ int msm_dsi_modeset_init(struct msm_dsi *msm_dsi, struct drm_device *dev,
 
 	return 0;
 fail:
-	if (msm_dsi) {
-		/* bridge/connector are normally destroyed by drm: */
-		if (msm_dsi->bridge) {
-			msm_dsi_manager_bridge_destroy(msm_dsi->bridge);
-			msm_dsi->bridge = NULL;
-		}
+	/* bridge/connector are normally destroyed by drm: */
+	if (msm_dsi->bridge) {
+		msm_dsi_manager_bridge_destroy(msm_dsi->bridge);
+		msm_dsi->bridge = NULL;
+	}
 
-		/* don't destroy connector if we didn't make it */
-		if (msm_dsi->connector && !msm_dsi->external_bridge)
-			msm_dsi->connector->funcs->destroy(msm_dsi->connector);
+	/* don't destroy connector if we didn't make it */
+	if (msm_dsi->connector && !msm_dsi->external_bridge)
+		msm_dsi->connector->funcs->destroy(msm_dsi->connector);
 
-		msm_dsi->connector = NULL;
-	}
+	msm_dsi->connector = NULL;
 
 	return ret;
 }