disp: msm: do not print error when crtc state is empty

Sometimes committed state doesn't contain any crtcs. For example,
fbdev emulation is still pushing null commits to DRM even if the
cable has been plugged out. Avoid flooding the logs in this case.

Change-Id: I6b7f049b80409c4a2ae057839ede6dd8af10d03b
Signed-off-by: Ray Zhang <[email protected]>
Signed-off-by: Steve Cohen <[email protected]>

msm/msm_atomic.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2016-2020, The Linux Foundation. All rights reserved.
  * Copyright (C) 2014 Red Hat
  * Author: Rob Clark <[email protected]>
  *
@@ -605,7 +605,7 @@ static void msm_atomic_commit_dispatch(struct drm_device *dev,
 	struct msm_drm_private *priv = dev->dev_private;
 	struct drm_crtc *crtc = NULL;
 	struct drm_crtc_state *crtc_state = NULL;
-	int ret = -EINVAL, i = 0, j = 0;
+	int ret = -ECANCELED, i = 0, j = 0;
 	bool nonblock;
 
 	/* cache since work will kfree commit in non-blocking case */
@@ -626,6 +626,7 @@ static void msm_atomic_commit_dispatch(struct drm_device *dev,
 				} else {
 					DRM_ERROR(" Error for crtc_id: %d\n",
 						priv->disp_thread[j].crtc_id);
+					ret = -EINVAL;
 				}
 				break;
 			}
@@ -641,13 +642,17 @@ static void msm_atomic_commit_dispatch(struct drm_device *dev,
 	}
 
 	if (ret) {
+		if (ret == -EINVAL)
+			DRM_ERROR("failed to dispatch commit to any CRTC\n");
+		else
+			DRM_DEBUG_DRIVER_RATELIMITED("empty crtc state\n");
+
 		/**
 		 * this is not expected to happen, but at this point the state
 		 * has been swapped, but we couldn't dispatch to a crtc thread.
 		 * fallback now to a synchronous complete_commit to try and
 		 * ensure that SW and HW state don't get out of sync.
 		 */
-		DRM_ERROR("failed to dispatch commit to any CRTC\n");
 		complete_commit(commit);
 	} else if (!nonblock) {
 		kthread_flush_work(&commit->commit_work);