[mirror_ubuntu-bionic-kernel.git] / drivers / gpu / drm / i915 / i915_gem_object.h

/*
 * Copyright © 2016 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

#ifndef __I915_GEM_OBJECT_H__
#define __I915_GEM_OBJECT_H__

#include <linux/reservation.h>

#include <drm/drm_vma_manager.h>
#include <drm/drm_gem.h>
#include <drm/drmP.h>

#include <drm/i915_drm.h>

struct drm_i915_gem_object_ops {
	unsigned int flags;
#define I915_GEM_OBJECT_HAS_STRUCT_PAGE 0x1
#define I915_GEM_OBJECT_IS_SHRINKABLE   0x2

	/* Interface between the GEM object and its backing storage.
	 * get_pages() is called once prior to the use of the associated set
	 * of pages before to binding them into the GTT, and put_pages() is
	 * called after we no longer need them. As we expect there to be
	 * associated cost with migrating pages between the backing storage
	 * and making them available for the GPU (e.g. clflush), we may hold
	 * onto the pages after they are no longer referenced by the GPU
	 * in case they may be used again shortly (for example migrating the
	 * pages to a different memory domain within the GTT). put_pages()
	 * will therefore most likely be called when the object itself is
	 * being released or under memory pressure (where we attempt to
	 * reap pages for the shrinker).
	 */
	struct sg_table *(*get_pages)(struct drm_i915_gem_object *);
	void (*put_pages)(struct drm_i915_gem_object *, struct sg_table *);

	int (*pwrite)(struct drm_i915_gem_object *,
		      const struct drm_i915_gem_pwrite *);

	int (*dmabuf_export)(struct drm_i915_gem_object *);
	void (*release)(struct drm_i915_gem_object *);
};

struct drm_i915_gem_object {
	struct drm_gem_object base;

	const struct drm_i915_gem_object_ops *ops;

	/** List of VMAs backed by this object */
	struct list_head vma_list;
	struct rb_root vma_tree;

	/** Stolen memory for this object, instead of being backed by shmem. */
	struct drm_mm_node *stolen;
	struct list_head global_link;
	union {
		struct rcu_head rcu;
		struct llist_node freed;
	};

	/**
	 * Whether the object is currently in the GGTT mmap.
	 */
	struct list_head userfault_link;

	/** Used in execbuf to temporarily hold a ref */
	struct list_head obj_exec_link;

	struct list_head batch_pool_link;

	unsigned long flags;

	/**
	 * Have we taken a reference for the object for incomplete GPU
	 * activity?
	 */
#define I915_BO_ACTIVE_REF 0

	/*
	 * Is the object to be mapped as read-only to the GPU
	 * Only honoured if hardware has relevant pte bit
	 */
	unsigned long gt_ro:1;
	unsigned int cache_level:3;
	unsigned int cache_dirty:1;

	atomic_t frontbuffer_bits;
	unsigned int frontbuffer_ggtt_origin; /* write once */
	struct i915_gem_active frontbuffer_write;

	/** Current tiling stride for the object, if it's tiled. */
	unsigned int tiling_and_stride;
#define FENCE_MINIMUM_STRIDE 128 /* See i915_tiling_ok() */
#define TILING_MASK (FENCE_MINIMUM_STRIDE-1)
#define STRIDE_MASK (~TILING_MASK)

	/** Count of VMA actually bound by this object */
	unsigned int bind_count;
	unsigned int active_count;
	unsigned int pin_display;

	struct {
		struct mutex lock; /* protects the pages and their use */
		atomic_t pages_pin_count;

		struct sg_table *pages;
		void *mapping;

		struct i915_gem_object_page_iter {
			struct scatterlist *sg_pos;
			unsigned int sg_idx; /* in pages, but 32bit eek! */

			struct radix_tree_root radix;
			struct mutex lock; /* protects this cache */
		} get_page;

		/**
		 * Advice: are the backing pages purgeable?
		 */
		unsigned int madv:2;

		/**
		 * This is set if the object has been written to since the
		 * pages were last acquired.
		 */
		bool dirty:1;

		/**
		 * This is set if the object has been pinned due to unknown
		 * swizzling.
		 */
		bool quirked:1;
	} mm;

	/** Breadcrumb of last rendering to the buffer.
	 * There can only be one writer, but we allow for multiple readers.
	 * If there is a writer that necessarily implies that all other
	 * read requests are complete - but we may only be lazily clearing
	 * the read requests. A read request is naturally the most recent
	 * request on a ring, so we may have two different write and read
	 * requests on one ring where the write request is older than the
	 * read request. This allows for the CPU to read from an active
	 * buffer by only waiting for the write to complete.
	 */
	struct reservation_object *resv;

	/** References from framebuffers, locks out tiling changes. */
	unsigned long framebuffer_references;

	/** Record of address bit 17 of each page at last unbind. */
	unsigned long *bit_17;

	struct i915_gem_userptr {
		uintptr_t ptr;
		unsigned read_only :1;

		struct i915_mm_struct *mm;
		struct i915_mmu_object *mmu_object;
		struct work_struct *work;
	} userptr;

	/** for phys allocated objects */
	struct drm_dma_handle *phys_handle;

	struct reservation_object __builtin_resv;
};

static inline struct drm_i915_gem_object *
to_intel_bo(struct drm_gem_object *gem)
{
	/* Assert that to_intel_bo(NULL) == NULL */
	BUILD_BUG_ON(offsetof(struct drm_i915_gem_object, base));

	return container_of(gem, struct drm_i915_gem_object, base);
}

/**
 * i915_gem_object_lookup_rcu - look up a temporary GEM object from its handle
 * @filp: DRM file private date
 * @handle: userspace handle
 *
 * Returns:
 *
 * A pointer to the object named by the handle if such exists on @filp, NULL
 * otherwise. This object is only valid whilst under the RCU read lock, and
 * note carefully the object may be in the process of being destroyed.
 */
static inline struct drm_i915_gem_object *
i915_gem_object_lookup_rcu(struct drm_file *file, u32 handle)
{
#ifdef CONFIG_LOCKDEP
	WARN_ON(debug_locks && !lock_is_held(&rcu_lock_map));
#endif
	return idr_find(&file->object_idr, handle);
}

static inline struct drm_i915_gem_object *
i915_gem_object_lookup(struct drm_file *file, u32 handle)
{
	struct drm_i915_gem_object *obj;

	rcu_read_lock();
	obj = i915_gem_object_lookup_rcu(file, handle);
	if (obj && !kref_get_unless_zero(&obj->base.refcount))
		obj = NULL;
	rcu_read_unlock();

	return obj;
}

__deprecated
extern struct drm_gem_object *
drm_gem_object_lookup(struct drm_file *file, u32 handle);

__attribute__((nonnull))
static inline struct drm_i915_gem_object *
i915_gem_object_get(struct drm_i915_gem_object *obj)
{
	drm_gem_object_reference(&obj->base);
	return obj;
}

__deprecated
extern void drm_gem_object_reference(struct drm_gem_object *);

__attribute__((nonnull))
static inline void
i915_gem_object_put(struct drm_i915_gem_object *obj)
{
	__drm_gem_object_unreference(&obj->base);
}

__deprecated
extern void drm_gem_object_unreference(struct drm_gem_object *);

__deprecated
extern void drm_gem_object_unreference_unlocked(struct drm_gem_object *);

static inline bool
i915_gem_object_is_dead(const struct drm_i915_gem_object *obj)
{
	return kref_read(&obj->base.refcount) == 0;
}

static inline bool
i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
{
	return obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE;
}

static inline bool
i915_gem_object_is_shrinkable(const struct drm_i915_gem_object *obj)
{
	return obj->ops->flags & I915_GEM_OBJECT_IS_SHRINKABLE;
}

static inline bool
i915_gem_object_is_active(const struct drm_i915_gem_object *obj)
{
	return obj->active_count;
}

static inline bool
i915_gem_object_has_active_reference(const struct drm_i915_gem_object *obj)
{
	return test_bit(I915_BO_ACTIVE_REF, &obj->flags);
}

static inline void
i915_gem_object_set_active_reference(struct drm_i915_gem_object *obj)
{
	lockdep_assert_held(&obj->base.dev->struct_mutex);
	__set_bit(I915_BO_ACTIVE_REF, &obj->flags);
}

static inline void
i915_gem_object_clear_active_reference(struct drm_i915_gem_object *obj)
{
	lockdep_assert_held(&obj->base.dev->struct_mutex);
	__clear_bit(I915_BO_ACTIVE_REF, &obj->flags);
}

void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj);

static inline unsigned int
i915_gem_object_get_tiling(struct drm_i915_gem_object *obj)
{
	return obj->tiling_and_stride & TILING_MASK;
}

static inline bool
i915_gem_object_is_tiled(struct drm_i915_gem_object *obj)
{
	return i915_gem_object_get_tiling(obj) != I915_TILING_NONE;
}

static inline unsigned int
i915_gem_object_get_stride(struct drm_i915_gem_object *obj)
{
	return obj->tiling_and_stride & STRIDE_MASK;
}

static inline unsigned int
i915_gem_tile_height(unsigned int tiling)
{
	GEM_BUG_ON(!tiling);
	return tiling == I915_TILING_Y ? 32 : 8;
}

static inline unsigned int
i915_gem_object_get_tile_height(struct drm_i915_gem_object *obj)
{
	return i915_gem_tile_height(i915_gem_object_get_tiling(obj));
}

static inline unsigned int
i915_gem_object_get_tile_row_size(struct drm_i915_gem_object *obj)
{
	return (i915_gem_object_get_stride(obj) *
		i915_gem_object_get_tile_height(obj));
}

int i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
			       unsigned int tiling, unsigned int stride);

static inline struct intel_engine_cs *
i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
{
	struct intel_engine_cs *engine = NULL;
	struct dma_fence *fence;

	rcu_read_lock();
	fence = reservation_object_get_excl_rcu(obj->resv);
	rcu_read_unlock();

	if (fence && dma_fence_is_i915(fence) && !dma_fence_is_signaled(fence))
		engine = to_request(fence)->engine;
	dma_fence_put(fence);

	return engine;
}

#endif
Commit	Line	Data
b42fe9ca JL	1	/*
	2	* Copyright © 2016 Intel Corporation
	3	*
	4	* Permission is hereby granted, free of charge, to any person obtaining a
	5	* copy of this software and associated documentation files (the "Software"),
	6	* to deal in the Software without restriction, including without limitation
	7	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	8	* and/or sell copies of the Software, and to permit persons to whom the
	9	* Software is furnished to do so, subject to the following conditions:
	10	*
	11	* The above copyright notice and this permission notice (including the next
	12	* paragraph) shall be included in all copies or substantial portions of the
	13	* Software.
	14	*
	15	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	16	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	17	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	18	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	19	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	20	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	21	* IN THE SOFTWARE.
	22	*
	23	*/
	24
	25	#ifndef __I915_GEM_OBJECT_H__
	26	#define __I915_GEM_OBJECT_H__
	27
	28	#include <linux/reservation.h>
	29
	30	#include <drm/drm_vma_manager.h>
	31	#include <drm/drm_gem.h>
	32	#include <drm/drmP.h>
	33
	34	#include <drm/i915_drm.h>
	35
	36	struct drm_i915_gem_object_ops {
	37	unsigned int flags;
	38	#define I915_GEM_OBJECT_HAS_STRUCT_PAGE 0x1
	39	#define I915_GEM_OBJECT_IS_SHRINKABLE 0x2
	40
	41	/* Interface between the GEM object and its backing storage.
	42	* get_pages() is called once prior to the use of the associated set
	43	* of pages before to binding them into the GTT, and put_pages() is
	44	* called after we no longer need them. As we expect there to be
	45	* associated cost with migrating pages between the backing storage
	46	* and making them available for the GPU (e.g. clflush), we may hold
	47	* onto the pages after they are no longer referenced by the GPU
	48	* in case they may be used again shortly (for example migrating the
	49	* pages to a different memory domain within the GTT). put_pages()
	50	* will therefore most likely be called when the object itself is
	51	* being released or under memory pressure (where we attempt to
	52	* reap pages for the shrinker).
	53	*/
	54	struct sg_table (get_pages)(struct drm_i915_gem_object *);
	55	void (put_pages)(struct drm_i915_gem_object , struct sg_table *);
	56
4e6fdafa CW	57	int (pwrite)(struct drm_i915_gem_object ,
	58	const struct drm_i915_gem_pwrite *);
	59
b42fe9ca JL	60	int (dmabuf_export)(struct drm_i915_gem_object );
	61	void (release)(struct drm_i915_gem_object );
	62	};
	63
	64	struct drm_i915_gem_object {
	65	struct drm_gem_object base;
	66
	67	const struct drm_i915_gem_object_ops *ops;
	68
	69	/** List of VMAs backed by this object */
	70	struct list_head vma_list;
	71	struct rb_root vma_tree;
	72
	73	/** Stolen memory for this object, instead of being backed by shmem. */
	74	struct drm_mm_node *stolen;
	75	struct list_head global_link;
	76	union {
	77	struct rcu_head rcu;
	78	struct llist_node freed;
	79	};
	80
	81	/**
	82	* Whether the object is currently in the GGTT mmap.
	83	*/
	84	struct list_head userfault_link;
	85
	86	/** Used in execbuf to temporarily hold a ref */
	87	struct list_head obj_exec_link;
	88
	89	struct list_head batch_pool_link;
	90
	91	unsigned long flags;
	92
	93	/**
	94	* Have we taken a reference for the object for incomplete GPU
	95	* activity?
	96	*/
	97	#define I915_BO_ACTIVE_REF 0
	98
	99	/*
	100	* Is the object to be mapped as read-only to the GPU
	101	* Only honoured if hardware has relevant pte bit
	102	*/
	103	unsigned long gt_ro:1;
	104	unsigned int cache_level:3;
	105	unsigned int cache_dirty:1;
	106
	107	atomic_t frontbuffer_bits;
	108	unsigned int frontbuffer_ggtt_origin; /* write once */
5b8c8aec	109	struct i915_gem_active frontbuffer_write;
b42fe9ca JL	110
	111	/** Current tiling stride for the object, if it's tiled. */
	112	unsigned int tiling_and_stride;
	113	#define FENCE_MINIMUM_STRIDE 128 /* See i915_tiling_ok() */
	114	#define TILING_MASK (FENCE_MINIMUM_STRIDE-1)
	115	#define STRIDE_MASK (~TILING_MASK)
	116
	117	/** Count of VMA actually bound by this object */
	118	unsigned int bind_count;
	119	unsigned int active_count;
	120	unsigned int pin_display;
	121
	122	struct {
	123	struct mutex lock; /* protects the pages and their use */
	124	atomic_t pages_pin_count;
	125
	126	struct sg_table *pages;
	127	void *mapping;
	128
	129	struct i915_gem_object_page_iter {
	130	struct scatterlist *sg_pos;
	131	unsigned int sg_idx; /* in pages, but 32bit eek! */
	132
	133	struct radix_tree_root radix;
	134	struct mutex lock; /* protects this cache */
	135	} get_page;
	136
	137	/**
	138	* Advice: are the backing pages purgeable?
	139	*/
	140	unsigned int madv:2;
	141
	142	/**
	143	* This is set if the object has been written to since the
	144	* pages were last acquired.
	145	*/
	146	bool dirty:1;
	147
	148	/**
	149	* This is set if the object has been pinned due to unknown
	150	* swizzling.
	151	*/
	152	bool quirked:1;
	153	} mm;
	154
	155	/** Breadcrumb of last rendering to the buffer.
	156	* There can only be one writer, but we allow for multiple readers.
	157	* If there is a writer that necessarily implies that all other
	158	* read requests are complete - but we may only be lazily clearing
	159	* the read requests. A read request is naturally the most recent
	160	* request on a ring, so we may have two different write and read
	161	* requests on one ring where the write request is older than the
	162	* read request. This allows for the CPU to read from an active
	163	* buffer by only waiting for the write to complete.
	164	*/
	165	struct reservation_object *resv;
	166
	167	/** References from framebuffers, locks out tiling changes. */
	168	unsigned long framebuffer_references;
	169
	170	/** Record of address bit 17 of each page at last unbind. */
	171	unsigned long *bit_17;
	172
	173	struct i915_gem_userptr {
174	uintptr_t ptr;
175	unsigned read_only :1;
176
177	struct i915_mm_struct *mm;
178	struct i915_mmu_object *mmu_object;
179	struct work_struct *work;
180	} userptr;
181
182	/** for phys allocated objects */
183	struct drm_dma_handle *phys_handle;
184
185	struct reservation_object __builtin_resv;
186	};
187
188	static inline struct drm_i915_gem_object *
189	to_intel_bo(struct drm_gem_object *gem)
190	{
191	/* Assert that to_intel_bo(NULL) == NULL */
192	BUILD_BUG_ON(offsetof(struct drm_i915_gem_object, base));
193
194	return container_of(gem, struct drm_i915_gem_object, base);
195	}
196
197	/**
198	* i915_gem_object_lookup_rcu - look up a temporary GEM object from its handle
199	* @filp: DRM file private date
200	* @handle: userspace handle
201	*
202	* Returns:
203	*
204	* A pointer to the object named by the handle if such exists on @filp, NULL
205	* otherwise. This object is only valid whilst under the RCU read lock, and
206	* note carefully the object may be in the process of being destroyed.
207	*/
208	static inline struct drm_i915_gem_object *
209	i915_gem_object_lookup_rcu(struct drm_file *file, u32 handle)
210	{
211	#ifdef CONFIG_LOCKDEP
212	WARN_ON(debug_locks && !lock_is_held(&rcu_lock_map));
213	#endif
214	return idr_find(&file->object_idr, handle);
215	}
216
217	static inline struct drm_i915_gem_object *
218	i915_gem_object_lookup(struct drm_file *file, u32 handle)
219	{
220	struct drm_i915_gem_object *obj;
221
222	rcu_read_lock();
223	obj = i915_gem_object_lookup_rcu(file, handle);
224	if (obj && !kref_get_unless_zero(&obj->base.refcount))
225	obj = NULL;
226	rcu_read_unlock();
227
228	return obj;
229	}
230
231	__deprecated
232	extern struct drm_gem_object *
233	drm_gem_object_lookup(struct drm_file *file, u32 handle);
234
235	__attribute__((nonnull))
236	static inline struct drm_i915_gem_object *
237	i915_gem_object_get(struct drm_i915_gem_object *obj)
238	{
239	drm_gem_object_reference(&obj->base);
240	return obj;
241	}
242
243	__deprecated
244	extern void drm_gem_object_reference(struct drm_gem_object *);
245
246	__attribute__((nonnull))
247	static inline void
248	i915_gem_object_put(struct drm_i915_gem_object *obj)
249	{
250	__drm_gem_object_unreference(&obj->base);
251	}
252
253	__deprecated
254	extern void drm_gem_object_unreference(struct drm_gem_object *);
255
256	__deprecated
257	extern void drm_gem_object_unreference_unlocked(struct drm_gem_object *);
258
259	static inline bool
260	i915_gem_object_is_dead(const struct drm_i915_gem_object *obj)
261	{
2c935bc5	262	return kref_read(&obj->base.refcount) == 0;
b42fe9ca JL	263	}
	264
	265	static inline bool
	266	i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
	267	{
	268	return obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE;
	269	}
	270
	271	static inline bool
	272	i915_gem_object_is_shrinkable(const struct drm_i915_gem_object *obj)
	273	{
	274	return obj->ops->flags & I915_GEM_OBJECT_IS_SHRINKABLE;
	275	}
	276
	277	static inline bool
	278	i915_gem_object_is_active(const struct drm_i915_gem_object *obj)
	279	{
	280	return obj->active_count;
	281	}
	282
	283	static inline bool
	284	i915_gem_object_has_active_reference(const struct drm_i915_gem_object *obj)
	285	{
	286	return test_bit(I915_BO_ACTIVE_REF, &obj->flags);
	287	}
	288
	289	static inline void
	290	i915_gem_object_set_active_reference(struct drm_i915_gem_object *obj)
	291	{
	292	lockdep_assert_held(&obj->base.dev->struct_mutex);
	293	__set_bit(I915_BO_ACTIVE_REF, &obj->flags);
	294	}
	295
	296	static inline void
	297	i915_gem_object_clear_active_reference(struct drm_i915_gem_object *obj)
	298	{
	299	lockdep_assert_held(&obj->base.dev->struct_mutex);
	300	__clear_bit(I915_BO_ACTIVE_REF, &obj->flags);
	301	}
	302
	303	void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj);
	304
	305	static inline unsigned int
	306	i915_gem_object_get_tiling(struct drm_i915_gem_object *obj)
	307	{
	308	return obj->tiling_and_stride & TILING_MASK;
	309	}
	310
	311	static inline bool
	312	i915_gem_object_is_tiled(struct drm_i915_gem_object *obj)
	313	{
	314	return i915_gem_object_get_tiling(obj) != I915_TILING_NONE;
	315	}
	316
	317	static inline unsigned int
	318	i915_gem_object_get_stride(struct drm_i915_gem_object *obj)
	319	{
	320	return obj->tiling_and_stride & STRIDE_MASK;
	321	}
	322
6649a0b6 CW	323	static inline unsigned int
	324	i915_gem_tile_height(unsigned int tiling)
	325	{
	326	GEM_BUG_ON(!tiling);
	327	return tiling == I915_TILING_Y ? 32 : 8;
	328	}
	329
	330	static inline unsigned int
	331	i915_gem_object_get_tile_height(struct drm_i915_gem_object *obj)
	332	{
	333	return i915_gem_tile_height(i915_gem_object_get_tiling(obj));
	334	}
	335
	336	static inline unsigned int
	337	i915_gem_object_get_tile_row_size(struct drm_i915_gem_object *obj)
	338	{
	339	return (i915_gem_object_get_stride(obj) *
	340	i915_gem_object_get_tile_height(obj));
	341	}
	342
957870f9 CW	343	int i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
	344	unsigned int tiling, unsigned int stride);
	345
b42fe9ca JL	346	static inline struct intel_engine_cs *
	347	i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
	348	{
	349	struct intel_engine_cs *engine = NULL;
	350	struct dma_fence *fence;
	351
	352	rcu_read_lock();
	353	fence = reservation_object_get_excl_rcu(obj->resv);
	354	rcu_read_unlock();
	355
	356	if (fence && dma_fence_is_i915(fence) && !dma_fence_is_signaled(fence))
	357	engine = to_request(fence)->engine;
	358	dma_fence_put(fence);
	359
	360	return engine;
	361	}
	362
	363	#endif
	364