drm/i915: Hold pc8 lock around toggling pc8.gpu_idle

We need to hold the pc8 lock around toggling the value of gpu_idle.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -6761,18 +6761,22 @@ static void hsw_update_package_c8(struct drm_device *dev)
 
 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)				\