drm: fix error recovery path in drm_crtc_helper_set_mode

There is no need to save or restore hwmode field, because by
the time this function sets this field, it cannot fail any more.
However, we should save old enabled field because if
the function fails, we want to return with unchanged CRTC.
Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc_helper.c

@@ -405,22 +405,25 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 			      struct drm_framebuffer *old_fb)
 {
 	struct drm_device *dev = crtc->dev;
-	struct drm_display_mode *adjusted_mode, saved_mode, saved_hwmode;
+	struct drm_display_mode *adjusted_mode, saved_mode;
 	struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
 	struct drm_encoder_helper_funcs *encoder_funcs;
 	int saved_x, saved_y;
+	bool saved_enabled;
 	struct drm_encoder *encoder;
 	bool ret = true;
 
+	saved_enabled = crtc->enabled;
 	crtc->enabled = drm_helper_crtc_in_use(crtc);
 	if (!crtc->enabled)
 		return true;
 
 	adjusted_mode = drm_mode_duplicate(dev, mode);
-	if (!adjusted_mode)
+	if (!adjusted_mode) {
+		crtc->enabled = saved_enabled;
 		return false;
+	}
 
-	saved_hwmode = crtc->hwmode;
 	saved_mode = crtc->mode;
 	saved_x = crtc->x;
 	saved_y = crtc->y;
@@ -539,7 +542,7 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 done:
 	drm_mode_destroy(dev, adjusted_mode);
 	if (!ret) {
-		crtc->hwmode = saved_hwmode;
+		crtc->enabled = saved_enabled;
 		crtc->mode = saved_mode;
 		crtc->x = saved_x;
 		crtc->y = saved_y;