drm/i915: Clear fence registers on GPU reset

When the GPU is reset, the fence registers are invalidated, so release
the objects and clear them out.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.c

@@ -395,7 +395,7 @@ int i915_reset(struct drm_device *dev, u8 flags)
 
 	mutex_lock(&dev->struct_mutex);
 
-	i915_gem_reset_lists(dev);
+	i915_gem_reset(dev);
 
 	/*
 	 * Set the domains we want to reset (GRDOM/bits 2 and 3) as

drivers/gpu/drm/i915/i915_drv.h

@@ -1033,7 +1033,7 @@ int i915_gem_object_get_fence_reg(struct drm_gem_object *obj,
 int i915_gem_object_put_fence_reg(struct drm_gem_object *obj,
 				  bool interruptible);
 void i915_gem_retire_requests(struct drm_device *dev);
-void i915_gem_reset_lists(struct drm_device *dev);
+void i915_gem_reset(struct drm_device *dev);
 void i915_gem_clflush_object(struct drm_gem_object *obj);
 int i915_gem_object_set_domain(struct drm_gem_object *obj,
 			       uint32_t read_domains,

drivers/gpu/drm/i915/i915_gem.c

@@ -1826,10 +1826,11 @@ static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
 	}
 }
 
-void i915_gem_reset_lists(struct drm_device *dev)
+void i915_gem_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj_priv;
+	int i;
 
 	i915_gem_reset_ring_lists(dev_priv, &dev_priv->render_ring);
 	if (HAS_BSD(dev))
@@ -1858,6 +1859,17 @@ void i915_gem_reset_lists(struct drm_device *dev)
 	{
 		obj_priv->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
 	}
+
+	/* The fence registers are invalidated so clear them out */
+	for (i = 0; i < 16; i++) {
+		struct drm_i915_fence_reg *reg;
+
+		reg = &dev_priv->fence_regs[i];
+		if (!reg->obj)
+			continue;
+
+		i915_gem_clear_fence_reg(reg->obj);
+	}
 }
 
 /**