disp: msm: avoid deadlock by prepending connection_mutex

Commit caused by dpms on may use extra  modeset lock on
connection_mutex before msm_atomic_commit, so to avoid
deadlock, make the modeset lock within msm_atomic_commit
to be used before the waiting for pending_crtcs_event.

Change-Id: Ic43af0f775d87ccc1d145ead9cb2e1b65018c86f
Signed-off-by: Mahadevan <[email protected]>

msm/msm_atomic.c

@@ -714,6 +714,16 @@ int msm_atomic_commit(struct drm_device *dev,
 		c->plane_mask |= (1 << drm_plane_index(plane));
 	}
 
+	/* Protection for prepare_fence callback */
+retry:
+	ret = drm_modeset_lock(&state->dev->mode_config.connection_mutex,
+		state->acquire_ctx);
+
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(state->acquire_ctx);
+		goto retry;
+	}
+
 	/*
 	 * Wait for pending updates on any of the same crtc's and then
 	 * mark our set of crtc's as busy:

msm/sde/sde_kms.c

@@ -1600,7 +1600,7 @@ static void sde_kms_prepare_fence(struct msm_kms *kms,
 {
 	struct drm_crtc *crtc;
 	struct drm_crtc_state *old_crtc_state;
-	int i, rc;
+	int i;
 
 	if (!kms || !old_state || !old_state->dev || !old_state->acquire_ctx) {
 		SDE_ERROR("invalid argument(s)\n");
@@ -1608,15 +1608,6 @@ static void sde_kms_prepare_fence(struct msm_kms *kms,
 	}
 
 	SDE_ATRACE_BEGIN("sde_kms_prepare_fence");
-retry:
-	/* attempt to acquire ww mutex for connection */
-	rc = drm_modeset_lock(&old_state->dev->mode_config.connection_mutex,
-			       old_state->acquire_ctx);
-
-	if (rc == -EDEADLK) {
-		drm_modeset_backoff(old_state->acquire_ctx);
-		goto retry;
-	}
 
 	/* old_state actually contains updated crtc pointers */
 	for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i) {