drm/i915: Balance assert_rpm_wakelock_held() for !IS_ENABLED(CONFIG_PM)

commit 0973128
Author: Imre Deak <imre.deak@intel.com>
Date:   Wed Feb 17 14:17:42 2016 +0200

    drm/i915: Add helper to get a display power ref if it was already enabled

left the rpm wakelock assertions unbalanced if CONFIG_PM was disabled as
intel_runtime_pm_get_if_in_use() would return true without incrementing
the local bookkeeping required for the assertions.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: Mika Kuoppala <mika.kuoppala@intel.com>
CC: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456434628-22574-1-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Imre Deak <imre.deak@intel.com>

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -2365,22 +2365,20 @@ bool intel_runtime_pm_get_if_in_use(struct drm_i915_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
 	struct device *device = &dev->pdev->dev;
-	int ret;
 
-	if (!IS_ENABLED(CONFIG_PM))
-		return true;
+	if (IS_ENABLED(CONFIG_PM)) {
+		int ret = pm_runtime_get_if_in_use(device);
 
-	ret = pm_runtime_get_if_in_use(device);
-
-	/*
-	 * In cases runtime PM is disabled by the RPM core and we get an
-	 * -EINVAL return value we are not supposed to call this function,
-	 * since the power state is undefined. This applies atm to the
-	 * late/early system suspend/resume handlers.
-	 */
-	WARN_ON_ONCE(ret < 0);
-	if (ret <= 0)
-		return false;
+		/*
+		 * In cases runtime PM is disabled by the RPM core and we get
+		 * an -EINVAL return value we are not supposed to call this
+		 * function, since the power state is undefined. This applies
+		 * atm to the late/early system suspend/resume handlers.
+		 */
+		WARN_ON_ONCE(ret < 0);
+		if (ret <= 0)
+			return false;
+	}
 
 	atomic_inc(&dev_priv->pm.wakeref_count);
 	assert_rpm_wakelock_held(dev_priv);