static void hsw_package_c8_gpu_idle(struct drm_i915_private *dev_priv)
 {
+       mutex_lock(&dev_priv->pc8.lock);
        if (!dev_priv->pc8.gpu_idle) {
                dev_priv->pc8.gpu_idle = true;
-               hsw_enable_package_c8(dev_priv);
+               __hsw_enable_package_c8(dev_priv);
        }
+       mutex_unlock(&dev_priv->pc8.lock);
 }
 
 static void hsw_package_c8_gpu_busy(struct drm_i915_private *dev_priv)
 {
+       mutex_lock(&dev_priv->pc8.lock);
        if (dev_priv->pc8.gpu_idle) {
                dev_priv->pc8.gpu_idle = false;
-               hsw_disable_package_c8(dev_priv);
+               __hsw_disable_package_c8(dev_priv);
        }
+       mutex_unlock(&dev_priv->pc8.lock);
 }
 
 #define for_each_power_domain(domain, mask)                            \