drm/i915: Check crtc_state->wm.need_postvbl_update before grabbing wm.mutex

wm.mutex does not protect the crtc state so no point in grabbing it
to check crtc_state->wm.need_postvbl_update.

Also do a bit of s/intel_crtc/crtc/ while at it.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190701160550.24205-1-ville.syrjala@linux.intel.comReviewed-by: Imre Deak <imre.deak@intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -1566,13 +1566,13 @@ static void g4x_optimize_watermarks(struct intel_atomic_state *state,
 				    struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
 
 	if (!crtc_state->wm.need_postvbl_update)
 		return;
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
-	intel_crtc->wm.active.g4x = crtc_state->wm.g4x.optimal;
+	crtc->wm.active.g4x = crtc_state->wm.g4x.optimal;
 	g4x_program_watermarks(dev_priv);
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }
@@ -2185,13 +2185,13 @@ static void vlv_optimize_watermarks(struct intel_atomic_state *state,
 				    struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
 
 	if (!crtc_state->wm.need_postvbl_update)
 		return;
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
-	intel_crtc->wm.active.vlv = crtc_state->wm.vlv.optimal;
+	crtc->wm.active.vlv = crtc_state->wm.vlv.optimal;
 	vlv_program_watermarks(dev_priv);
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }
@@ -5723,10 +5723,10 @@ static void ilk_initial_watermarks(struct intel_atomic_state *state,
 				   struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
-	intel_crtc->wm.active.ilk = crtc_state->wm.ilk.intermediate;
+	crtc->wm.active.ilk = crtc_state->wm.ilk.intermediate;
 	ilk_program_watermarks(dev_priv);
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }
@@ -5735,13 +5735,14 @@ static void ilk_optimize_watermarks(struct intel_atomic_state *state,
 				    struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
+
+	if (!crtc_state->wm.need_postvbl_update)
+		return;
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
-	if (crtc_state->wm.need_postvbl_update) {
-		intel_crtc->wm.active.ilk = crtc_state->wm.ilk.optimal;
+	crtc->wm.active.ilk = crtc_state->wm.ilk.optimal;
 	ilk_program_watermarks(dev_priv);
-	}
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }