1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * (C) COPYRIGHT 2016 ARM Limited. All rights reserved.
4  * Author: Brian Starkey <brian.starkey@arm.com>
5  *
6  * This program is free software and is provided to you under the terms of the
7  * GNU General Public License version 2 as published by the Free Software
8  * Foundation, and any use by you of this program is subject to the terms
9  * of such GNU licence.
10  */
11 
12 #include <linux/dma-fence.h>
13 
14 #include <drm/drm_crtc.h>
15 #include <drm/drm_device.h>
16 #include <drm/drm_drv.h>
17 #include <drm/drm_framebuffer.h>
18 #include <drm/drm_managed.h>
19 #include <drm/drm_modeset_helper_vtables.h>
20 #include <drm/drm_property.h>
21 #include <drm/drm_writeback.h>
22 
23 /**
24  * DOC: overview
25  *
26  * Writeback connectors are used to expose hardware which can write the output
27  * from a CRTC to a memory buffer. They are used and act similarly to other
28  * types of connectors, with some important differences:
29  *
30  * * Writeback connectors don't provide a way to output visually to the user.
31  *
32  * * Writeback connectors are visible to userspace only when the client sets
33  *   DRM_CLIENT_CAP_WRITEBACK_CONNECTORS.
34  *
35  * * Writeback connectors don't have EDID.
36  *
37  * A framebuffer may only be attached to a writeback connector when the
38  * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the
39  * framebuffer applies only to a single commit (see below). A framebuffer may
40  * not be attached while the CRTC is off.
41  *
42  * Unlike with planes, when a writeback framebuffer is removed by userspace DRM
43  * makes no attempt to remove it from active use by the connector. This is
44  * because no method is provided to abort a writeback operation, and in any
45  * case making a new commit whilst a writeback is ongoing is undefined (see
46  * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished,
47  * the framebuffer will automatically no longer be in active use. As it will
48  * also have already been removed from the framebuffer list, there will be no
49  * way for any userspace application to retrieve a reference to it in the
50  * intervening period.
51  *
52  * Writeback connectors have some additional properties, which userspace
53  * can use to query and control them:
54  *
55  *  "WRITEBACK_FB_ID":
56  *	Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the
57  *	framebuffer to be written by the writeback connector. This property is
58  *	similar to the FB_ID property on planes, but will always read as zero
59  *	and is not preserved across commits.
60  *	Userspace must set this property to an output buffer every time it
61  *	wishes the buffer to get filled.
62  *
63  *  "WRITEBACK_PIXEL_FORMATS":
64  *	Immutable blob property to store the supported pixel formats table. The
65  *	data is an array of u32 DRM_FORMAT_* fourcc values.
66  *	Userspace can use this blob to find out what pixel formats are supported
67  *	by the connector's writeback engine.
68  *
69  *  "WRITEBACK_OUT_FENCE_PTR":
70  *	Userspace can use this property to provide a pointer for the kernel to
71  *	fill with a sync_file file descriptor, which will signal once the
72  *	writeback is finished. The value should be the address of a 32-bit
73  *	signed integer, cast to a u64.
74  *	Userspace should wait for this fence to signal before making another
75  *	commit affecting any of the same CRTCs, Planes or Connectors.
76  *	**Failure to do so will result in undefined behaviour.**
77  *	For this reason it is strongly recommended that all userspace
78  *	applications making use of writeback connectors *always* retrieve an
79  *	out-fence for the commit and use it appropriately.
80  *	From userspace, this property will always read as zero.
81  */
82 
83 #define fence_to_wb_connector(x) container_of(x->lock, \
84 					      struct drm_writeback_connector, \
85 					      fence_lock)
86 
drm_writeback_fence_get_driver_name(struct dma_fence * fence)87 static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence)
88 {
89 	struct drm_writeback_connector *wb_connector =
90 		fence_to_wb_connector(fence);
91 
92 	return wb_connector->base.dev->driver->name;
93 }
94 
95 static const char *
drm_writeback_fence_get_timeline_name(struct dma_fence * fence)96 drm_writeback_fence_get_timeline_name(struct dma_fence *fence)
97 {
98 	struct drm_writeback_connector *wb_connector =
99 		fence_to_wb_connector(fence);
100 
101 	return wb_connector->timeline_name;
102 }
103 
104 static const struct dma_fence_ops drm_writeback_fence_ops = {
105 	.get_driver_name = drm_writeback_fence_get_driver_name,
106 	.get_timeline_name = drm_writeback_fence_get_timeline_name,
107 };
108 
create_writeback_properties(struct drm_device * dev)109 static int create_writeback_properties(struct drm_device *dev)
110 {
111 	struct drm_property *prop;
112 
113 	if (!dev->mode_config.writeback_fb_id_property) {
114 		prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
115 						  "WRITEBACK_FB_ID",
116 						  DRM_MODE_OBJECT_FB);
117 		if (!prop)
118 			return -ENOMEM;
119 		dev->mode_config.writeback_fb_id_property = prop;
120 	}
121 
122 	if (!dev->mode_config.writeback_pixel_formats_property) {
123 		prop = drm_property_create(dev, DRM_MODE_PROP_BLOB |
124 					   DRM_MODE_PROP_ATOMIC |
125 					   DRM_MODE_PROP_IMMUTABLE,
126 					   "WRITEBACK_PIXEL_FORMATS", 0);
127 		if (!prop)
128 			return -ENOMEM;
129 		dev->mode_config.writeback_pixel_formats_property = prop;
130 	}
131 
132 	if (!dev->mode_config.writeback_out_fence_ptr_property) {
133 		prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
134 						 "WRITEBACK_OUT_FENCE_PTR", 0,
135 						 U64_MAX);
136 		if (!prop)
137 			return -ENOMEM;
138 		dev->mode_config.writeback_out_fence_ptr_property = prop;
139 	}
140 
141 	return 0;
142 }
143 
144 static const struct drm_encoder_funcs drm_writeback_encoder_funcs = {
145 	.destroy = drm_encoder_cleanup,
146 };
147 
148 /**
149  * drm_writeback_connector_init - Initialize a writeback connector and its properties
150  * @dev: DRM device
151  * @wb_connector: Writeback connector to initialize
152  * @con_funcs: Connector funcs vtable
153  * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder
154  * @formats: Array of supported pixel formats for the writeback engine
155  * @n_formats: Length of the formats array
156  * @possible_crtcs: possible crtcs for the internal writeback encoder
157  *
158  * This function creates the writeback-connector-specific properties if they
159  * have not been already created, initializes the connector as
160  * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
161  * values. It will also create an internal encoder associated with the
162  * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for
163  * the encoder helper.
164  *
165  * Drivers should always use this function instead of drm_connector_init() to
166  * set up writeback connectors.
167  *
168  * Returns: 0 on success, or a negative error code
169  */
drm_writeback_connector_init(struct drm_device * dev,struct drm_writeback_connector * wb_connector,const struct drm_connector_funcs * con_funcs,const struct drm_encoder_helper_funcs * enc_helper_funcs,const u32 * formats,int n_formats,u32 possible_crtcs)170 int drm_writeback_connector_init(struct drm_device *dev,
171 				 struct drm_writeback_connector *wb_connector,
172 				 const struct drm_connector_funcs *con_funcs,
173 				 const struct drm_encoder_helper_funcs *enc_helper_funcs,
174 				 const u32 *formats, int n_formats,
175 				 u32 possible_crtcs)
176 {
177 	int ret = 0;
178 
179 	drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
180 
181 	wb_connector->encoder.possible_crtcs = possible_crtcs;
182 
183 	ret = drm_encoder_init(dev, &wb_connector->encoder,
184 			       &drm_writeback_encoder_funcs,
185 			       DRM_MODE_ENCODER_VIRTUAL, NULL);
186 	if (ret)
187 		return ret;
188 
189 	ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder,
190 			con_funcs, formats, n_formats);
191 
192 	if (ret)
193 		drm_encoder_cleanup(&wb_connector->encoder);
194 
195 	return ret;
196 }
197 EXPORT_SYMBOL(drm_writeback_connector_init);
198 
delete_writeback_properties(struct drm_device * dev)199 static void delete_writeback_properties(struct drm_device *dev)
200 {
201 	if (dev->mode_config.writeback_pixel_formats_property) {
202 		drm_property_destroy(dev, dev->mode_config.writeback_pixel_formats_property);
203 		dev->mode_config.writeback_pixel_formats_property = NULL;
204 	}
205 	if (dev->mode_config.writeback_out_fence_ptr_property) {
206 		drm_property_destroy(dev, dev->mode_config.writeback_out_fence_ptr_property);
207 		dev->mode_config.writeback_out_fence_ptr_property = NULL;
208 	}
209 	if (dev->mode_config.writeback_fb_id_property) {
210 		drm_property_destroy(dev, dev->mode_config.writeback_fb_id_property);
211 		dev->mode_config.writeback_fb_id_property = NULL;
212 	}
213 }
214 
215 /**
216  * __drm_writeback_connector_init - Initialize a writeback connector with
217  * a custom encoder
218  *
219  * @dev: DRM device
220  * @wb_connector: Writeback connector to initialize
221  * @enc: handle to the already initialized drm encoder
222  * @formats: Array of supported pixel formats for the writeback engine
223  * @n_formats: Length of the formats array
224  *
225  * This function creates the writeback-connector-specific properties if they
226  * have not been already created, initializes the connector as
227  * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
228  * values.
229  *
230  * This function assumes that the drm_writeback_connector's encoder has already been
231  * created and initialized before invoking this function.
232  *
233  * In addition, this function also assumes that callers of this API will manage
234  * assigning the encoder helper functions, possible_crtcs and any other encoder
235  * specific operation.
236  *
237  * Returns: 0 on success, or a negative error code
238  */
__drm_writeback_connector_init(struct drm_device * dev,struct drm_writeback_connector * wb_connector,struct drm_encoder * enc,const u32 * formats,int n_formats)239 static int __drm_writeback_connector_init(struct drm_device *dev,
240 					  struct drm_writeback_connector *wb_connector,
241 					  struct drm_encoder *enc, const u32 *formats,
242 					  int n_formats)
243 {
244 	struct drm_connector *connector = &wb_connector->base;
245 	struct drm_mode_config *config = &dev->mode_config;
246 	struct drm_property_blob *blob;
247 	int ret = create_writeback_properties(dev);
248 
249 	if (ret != 0)
250 		goto failed_properties;
251 
252 	connector->interlace_allowed = 0;
253 
254 	ret = drm_connector_attach_encoder(connector, enc);
255 	if (ret)
256 		goto failed_properties;
257 
258 	blob = drm_property_create_blob(dev, n_formats * sizeof(*formats),
259 					formats);
260 	if (IS_ERR(blob)) {
261 		ret = PTR_ERR(blob);
262 		goto failed_properties;
263 	}
264 
265 	INIT_LIST_HEAD(&wb_connector->job_queue);
266 	spin_lock_init(&wb_connector->job_lock);
267 
268 	wb_connector->fence_context = dma_fence_context_alloc(1);
269 	spin_lock_init(&wb_connector->fence_lock);
270 	snprintf(wb_connector->timeline_name,
271 		 sizeof(wb_connector->timeline_name),
272 		 "CONNECTOR:%d-%s", connector->base.id, connector->name);
273 
274 	drm_object_attach_property(&connector->base,
275 				   config->writeback_out_fence_ptr_property, 0);
276 
277 	drm_object_attach_property(&connector->base,
278 				   config->writeback_fb_id_property, 0);
279 
280 	drm_object_attach_property(&connector->base,
281 				   config->writeback_pixel_formats_property,
282 				   blob->base.id);
283 	wb_connector->pixel_formats_blob_ptr = blob;
284 
285 	return 0;
286 failed_properties:
287 	delete_writeback_properties(dev);
288 	return ret;
289 }
290 
291 /**
292  * drm_writeback_connector_init_with_encoder - Initialize a writeback connector with
293  * a custom encoder
294  *
295  * @dev: DRM device
296  * @wb_connector: Writeback connector to initialize
297  * @enc: handle to the already initialized drm encoder
298  * @con_funcs: Connector funcs vtable
299  * @formats: Array of supported pixel formats for the writeback engine
300  * @n_formats: Length of the formats array
301  *
302  * This function creates the writeback-connector-specific properties if they
303  * have not been already created, initializes the connector as
304  * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
305  * values.
306  *
307  * This function assumes that the drm_writeback_connector's encoder has already been
308  * created and initialized before invoking this function.
309  *
310  * In addition, this function also assumes that callers of this API will manage
311  * assigning the encoder helper functions, possible_crtcs and any other encoder
312  * specific operation.
313  *
314  * Drivers should always use this function instead of drm_connector_init() to
315  * set up writeback connectors if they want to manage themselves the lifetime of the
316  * associated encoder.
317  *
318  * Returns: 0 on success, or a negative error code
319  */
drm_writeback_connector_init_with_encoder(struct drm_device * dev,struct drm_writeback_connector * wb_connector,struct drm_encoder * enc,const struct drm_connector_funcs * con_funcs,const u32 * formats,int n_formats)320 int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
321 					      struct drm_writeback_connector *wb_connector,
322 					      struct drm_encoder *enc,
323 					      const struct drm_connector_funcs *con_funcs,
324 					      const u32 *formats, int n_formats)
325 {
326 	struct drm_connector *connector = &wb_connector->base;
327 	int ret;
328 
329 	ret = drm_connector_init(dev, connector, con_funcs,
330 				 DRM_MODE_CONNECTOR_WRITEBACK);
331 	if (ret)
332 		return ret;
333 
334 	ret = __drm_writeback_connector_init(dev, wb_connector, enc, formats,
335 					     n_formats);
336 	if (ret)
337 		drm_connector_cleanup(connector);
338 
339 	return ret;
340 }
341 EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder);
342 
343 /**
344  * drm_writeback_connector_cleanup - Cleanup the writeback connector
345  * @dev: DRM device
346  * @wb_connector: Pointer to the writeback connector to clean up
347  *
348  * This will decrement the reference counter of blobs and destroy properties. It
349  * will also clean the remaining jobs in this writeback connector. Caution: This helper will not
350  * clean up the attached encoder and the drm_connector.
351  */
drm_writeback_connector_cleanup(struct drm_device * dev,struct drm_writeback_connector * wb_connector)352 static void drm_writeback_connector_cleanup(struct drm_device *dev,
353 					    struct drm_writeback_connector *wb_connector)
354 {
355 	unsigned long flags;
356 	struct drm_writeback_job *pos, *n;
357 
358 	delete_writeback_properties(dev);
359 	drm_property_blob_put(wb_connector->pixel_formats_blob_ptr);
360 
361 	spin_lock_irqsave(&wb_connector->job_lock, flags);
362 	list_for_each_entry_safe(pos, n, &wb_connector->job_queue, list_entry) {
363 		list_del(&pos->list_entry);
364 		drm_writeback_cleanup_job(pos);
365 	}
366 	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
367 }
368 
369 /**
370  * drmm_writeback_connector_init - Initialize a writeback connector with
371  * a custom encoder
372  *
373  * @dev: DRM device
374  * @wb_connector: Writeback connector to initialize
375  * @con_funcs: Connector funcs vtable
376  * @enc: Encoder to connect this writeback connector
377  * @formats: Array of supported pixel formats for the writeback engine
378  * @n_formats: Length of the formats array
379  *
380  * This function initialize a writeback connector and register its cleanup.
381  *
382  * This function creates the writeback-connector-specific properties if they
383  * have not been already created, initializes the connector as
384  * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
385  * values.
386  *
387  * Returns: 0 on success, or a negative error code
388  */
drmm_writeback_connector_init(struct drm_device * dev,struct drm_writeback_connector * wb_connector,const struct drm_connector_funcs * con_funcs,struct drm_encoder * enc,const u32 * formats,int n_formats)389 int drmm_writeback_connector_init(struct drm_device *dev,
390 				  struct drm_writeback_connector *wb_connector,
391 				  const struct drm_connector_funcs *con_funcs,
392 				  struct drm_encoder *enc,
393 				  const u32 *formats, int n_formats)
394 {
395 	struct drm_connector *connector = &wb_connector->base;
396 	int ret;
397 
398 	ret = drmm_connector_init(dev, connector, con_funcs,
399 				  DRM_MODE_CONNECTOR_WRITEBACK, NULL);
400 	if (ret)
401 		return ret;
402 
403 	ret = __drm_writeback_connector_init(dev, wb_connector, enc, formats,
404 					     n_formats);
405 	if (ret)
406 		return ret;
407 
408 	ret = drmm_add_action_or_reset(dev, (void *)drm_writeback_connector_cleanup,
409 				       wb_connector);
410 	if (ret)
411 		return ret;
412 
413 	return 0;
414 }
415 EXPORT_SYMBOL(drmm_writeback_connector_init);
416 
drm_writeback_set_fb(struct drm_connector_state * conn_state,struct drm_framebuffer * fb)417 int drm_writeback_set_fb(struct drm_connector_state *conn_state,
418 			 struct drm_framebuffer *fb)
419 {
420 	WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);
421 
422 	if (!conn_state->writeback_job) {
423 		conn_state->writeback_job =
424 			kzalloc(sizeof(*conn_state->writeback_job), GFP_KERNEL);
425 		if (!conn_state->writeback_job)
426 			return -ENOMEM;
427 
428 		conn_state->writeback_job->connector =
429 			drm_connector_to_writeback(conn_state->connector);
430 	}
431 
432 	drm_framebuffer_assign(&conn_state->writeback_job->fb, fb);
433 	return 0;
434 }
435 
drm_writeback_prepare_job(struct drm_writeback_job * job)436 int drm_writeback_prepare_job(struct drm_writeback_job *job)
437 {
438 	struct drm_writeback_connector *connector = job->connector;
439 	const struct drm_connector_helper_funcs *funcs =
440 		connector->base.helper_private;
441 	int ret;
442 
443 	if (funcs->prepare_writeback_job) {
444 		ret = funcs->prepare_writeback_job(connector, job);
445 		if (ret < 0)
446 			return ret;
447 	}
448 
449 	job->prepared = true;
450 	return 0;
451 }
452 EXPORT_SYMBOL(drm_writeback_prepare_job);
453 
454 /**
455  * drm_writeback_queue_job - Queue a writeback job for later signalling
456  * @wb_connector: The writeback connector to queue a job on
457  * @conn_state: The connector state containing the job to queue
458  *
459  * This function adds the job contained in @conn_state to the job_queue for a
460  * writeback connector. It takes ownership of the writeback job and sets the
461  * @conn_state->writeback_job to NULL, and so no access to the job may be
462  * performed by the caller after this function returns.
463  *
464  * Drivers must ensure that for a given writeback connector, jobs are queued in
465  * exactly the same order as they will be completed by the hardware (and
466  * signaled via drm_writeback_signal_completion).
467  *
468  * For every call to drm_writeback_queue_job() there must be exactly one call to
469  * drm_writeback_signal_completion()
470  *
471  * See also: drm_writeback_signal_completion()
472  */
drm_writeback_queue_job(struct drm_writeback_connector * wb_connector,struct drm_connector_state * conn_state)473 void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
474 			     struct drm_connector_state *conn_state)
475 {
476 	struct drm_writeback_job *job;
477 	unsigned long flags;
478 
479 	job = conn_state->writeback_job;
480 	conn_state->writeback_job = NULL;
481 
482 	spin_lock_irqsave(&wb_connector->job_lock, flags);
483 	list_add_tail(&job->list_entry, &wb_connector->job_queue);
484 	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
485 }
486 EXPORT_SYMBOL(drm_writeback_queue_job);
487 
drm_writeback_cleanup_job(struct drm_writeback_job * job)488 void drm_writeback_cleanup_job(struct drm_writeback_job *job)
489 {
490 	struct drm_writeback_connector *connector = job->connector;
491 	const struct drm_connector_helper_funcs *funcs =
492 		connector->base.helper_private;
493 
494 	if (job->prepared && funcs->cleanup_writeback_job)
495 		funcs->cleanup_writeback_job(connector, job);
496 
497 	if (job->fb)
498 		drm_framebuffer_put(job->fb);
499 
500 	if (job->out_fence)
501 		dma_fence_put(job->out_fence);
502 
503 	kfree(job);
504 }
505 EXPORT_SYMBOL(drm_writeback_cleanup_job);
506 
507 /*
508  * @cleanup_work: deferred cleanup of a writeback job
509  *
510  * The job cannot be cleaned up directly in drm_writeback_signal_completion,
511  * because it may be called in interrupt context. Dropping the framebuffer
512  * reference can sleep, and so the cleanup is deferred to a workqueue.
513  */
cleanup_work(struct work_struct * work)514 static void cleanup_work(struct work_struct *work)
515 {
516 	struct drm_writeback_job *job = container_of(work,
517 						     struct drm_writeback_job,
518 						     cleanup_work);
519 
520 	drm_writeback_cleanup_job(job);
521 }
522 
523 /**
524  * drm_writeback_signal_completion - Signal the completion of a writeback job
525  * @wb_connector: The writeback connector whose job is complete
526  * @status: Status code to set in the writeback out_fence (0 for success)
527  *
528  * Drivers should call this to signal the completion of a previously queued
529  * writeback job. It should be called as soon as possible after the hardware
530  * has finished writing, and may be called from interrupt context.
531  * It is the driver's responsibility to ensure that for a given connector, the
532  * hardware completes writeback jobs in the same order as they are queued.
533  *
534  * Unless the driver is holding its own reference to the framebuffer, it must
535  * not be accessed after calling this function.
536  *
537  * See also: drm_writeback_queue_job()
538  */
539 void
drm_writeback_signal_completion(struct drm_writeback_connector * wb_connector,int status)540 drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector,
541 				int status)
542 {
543 	unsigned long flags;
544 	struct drm_writeback_job *job;
545 	struct dma_fence *out_fence;
546 
547 	spin_lock_irqsave(&wb_connector->job_lock, flags);
548 	job = list_first_entry_or_null(&wb_connector->job_queue,
549 				       struct drm_writeback_job,
550 				       list_entry);
551 	if (job)
552 		list_del(&job->list_entry);
553 
554 	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
555 
556 	if (WARN_ON(!job))
557 		return;
558 
559 	out_fence = job->out_fence;
560 	if (out_fence) {
561 		if (status)
562 			dma_fence_set_error(out_fence, status);
563 		dma_fence_signal(out_fence);
564 		dma_fence_put(out_fence);
565 		job->out_fence = NULL;
566 	}
567 
568 	INIT_WORK(&job->cleanup_work, cleanup_work);
569 	queue_work(system_long_wq, &job->cleanup_work);
570 }
571 EXPORT_SYMBOL(drm_writeback_signal_completion);
572 
573 struct dma_fence *
drm_writeback_get_out_fence(struct drm_writeback_connector * wb_connector)574 drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector)
575 {
576 	struct dma_fence *fence;
577 
578 	if (WARN_ON(wb_connector->base.connector_type !=
579 		    DRM_MODE_CONNECTOR_WRITEBACK))
580 		return NULL;
581 
582 	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
583 	if (!fence)
584 		return NULL;
585 
586 	dma_fence_init(fence, &drm_writeback_fence_ops,
587 		       &wb_connector->fence_lock, wb_connector->fence_context,
588 		       ++wb_connector->fence_seqno);
589 
590 	return fence;
591 }
592 EXPORT_SYMBOL(drm_writeback_get_out_fence);
593