diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 1a7ac2eefe97..5fe27e42d81b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -801,6 +801,7 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
 	spin_lock_init(&dev_priv->uncore.lock);
 	spin_lock_init(&dev_priv->mm.object_stat_lock);
 	spin_lock_init(&dev_priv->mmio_flip_lock);
+	spin_lock_init(&dev_priv->wm.dsparb_lock);
 	mutex_init(&dev_priv->sb_lock);
 	mutex_init(&dev_priv->modeset_restore_lock);
 	mutex_init(&dev_priv->av_mutex);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8daa4fb13b52..33758ac5ec9a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2191,6 +2191,9 @@ struct drm_i915_private {
 	} sagv_status;
 
 	struct {
+		/* protects DSPARB registers on pre-g4x/vlv/chv */
+		spinlock_t dsparb_lock;
+
 		/*
 		 * Raw watermark latency values:
 		 * in 0.1us units for WM0,
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index c6fe59944a0b..3ea7cf275be0 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1223,6 +1223,8 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc *crtc)
 		      pipe_name(crtc->pipe), sprite0_start,
 		      sprite1_start, fifo_size);
 
+	spin_lock(&dev_priv->wm.dsparb_lock);
+
 	switch (crtc->pipe) {
 		uint32_t dsparb, dsparb2, dsparb3;
 	case PIPE_A:
@@ -1279,6 +1281,10 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc *crtc)
 	default:
 		break;
 	}
+
+	POSTING_READ(DSPARB);
+
+	spin_unlock(&dev_priv->wm.dsparb_lock);
 }
 
 #undef VLV_FIFO