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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * (C) COPYRIGHT 2016 ARM Limited. All rights reserved.
4 * Author: Brian Starkey <[email protected]>
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#include <linux/export.h>
14
15#include <drm/drm_crtc.h>
16#include <drm/drm_device.h>
17#include <drm/drm_drv.h>
18#include <drm/drm_framebuffer.h>
19#include <drm/drm_managed.h>
20#include <drm/drm_modeset_helper_vtables.h>
21#include <drm/drm_property.h>
22#include <drm/drm_writeback.h>
23
24/**
25 * DOC: overview
26 *
27 * Writeback connectors are used to expose hardware which can write the output
28 * from a CRTC to a memory buffer. They are used and act similarly to other
29 * types of connectors, with some important differences:
30 *
31 * * Writeback connectors don't provide a way to output visually to the user.
32 *
33 * * Writeback connectors are visible to userspace only when the client sets
34 * DRM_CLIENT_CAP_WRITEBACK_CONNECTORS.
35 *
36 * * Writeback connectors don't have EDID.
37 *
38 * A framebuffer may only be attached to a writeback connector when the
39 * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the
40 * framebuffer applies only to a single commit (see below). A framebuffer may
41 * not be attached while the CRTC is off.
42 *
43 * Unlike with planes, when a writeback framebuffer is removed by userspace DRM
44 * makes no attempt to remove it from active use by the connector. This is
45 * because no method is provided to abort a writeback operation, and in any
46 * case making a new commit whilst a writeback is ongoing is undefined (see
47 * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished,
48 * the framebuffer will automatically no longer be in active use. As it will
49 * also have already been removed from the framebuffer list, there will be no
50 * way for any userspace application to retrieve a reference to it in the
51 * intervening period.
52 *
53 * Writeback connectors have some additional properties, which userspace
54 * can use to query and control them:
55 *
56 * "WRITEBACK_FB_ID":
57 * Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the
58 * framebuffer to be written by the writeback connector. This property is
59 * similar to the FB_ID property on planes, but will always read as zero
60 * and is not preserved across commits.
61 * If the width and height of the framebuffer do not match those of the
62 * attached CRTC, the driver must either fail or scale (not crop) the
63 * content to exactly fit the framebuffer.
64 * If the driver is unable to exactly fill the framebuffer for any reason,
65 * such as hardware scaler constraints or an odd width for a sub-sampled
66 * format, the writeback must fail instead of partially filling the buffer.
67 * Userspace must set this property to an output buffer every time it
68 * wishes the buffer to get filled.
69 *
70 * "WRITEBACK_PIXEL_FORMATS":
71 * Immutable blob property to store the supported pixel formats table. The
72 * data is an array of u32 DRM_FORMAT_* fourcc values.
73 * Userspace can use this blob to find out what pixel formats are supported
74 * by the connector's writeback engine.
75 *
76 * "WRITEBACK_OUT_FENCE_PTR":
77 * Userspace can use this property to provide a pointer for the kernel to
78 * fill with a sync_file file descriptor, which will signal once the
79 * writeback is finished. The value should be the address of a 32-bit
80 * signed integer, cast to a u64.
81 * Userspace should wait for this fence to signal before making another
82 * commit affecting any of the same CRTCs, Planes or Connectors.
83 * **Failure to do so will result in undefined behaviour.**
84 * For this reason it is strongly recommended that all userspace
85 * applications making use of writeback connectors *always* retrieve an
86 * out-fence for the commit and use it appropriately.
87 * From userspace, this property will always read as zero.
88 */
89
90#define fence_to_wb_connector(x) container_of(x->extern_lock, \
91 struct drm_writeback_connector, \
92 fence_lock)
93
94static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence)
95{
96 struct drm_writeback_connector *wb_connector =
97 fence_to_wb_connector(fence);
98
99 return wb_connector->base.dev->driver->name;
100}
101
102static const char *
103drm_writeback_fence_get_timeline_name(struct dma_fence *fence)
104{
105 struct drm_writeback_connector *wb_connector =
106 fence_to_wb_connector(fence);
107
108 return wb_connector->timeline_name;
109}
110
111static const struct dma_fence_ops drm_writeback_fence_ops = {
112 .get_driver_name = drm_writeback_fence_get_driver_name,
113 .get_timeline_name = drm_writeback_fence_get_timeline_name,
114};
115
116static int create_writeback_properties(struct drm_device *dev)
117{
118 struct drm_property *prop;
119
120 if (!dev->mode_config.writeback_fb_id_property) {
121 prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
122 "WRITEBACK_FB_ID",
123 DRM_MODE_OBJECT_FB);
124 if (!prop)
125 return -ENOMEM;
126 dev->mode_config.writeback_fb_id_property = prop;
127 }
128
129 if (!dev->mode_config.writeback_pixel_formats_property) {
130 prop = drm_property_create(dev, DRM_MODE_PROP_BLOB |
131 DRM_MODE_PROP_ATOMIC |
132 DRM_MODE_PROP_IMMUTABLE,
133 "WRITEBACK_PIXEL_FORMATS", 0);
134 if (!prop)
135 return -ENOMEM;
136 dev->mode_config.writeback_pixel_formats_property = prop;
137 }
138
139 if (!dev->mode_config.writeback_out_fence_ptr_property) {
140 prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
141 "WRITEBACK_OUT_FENCE_PTR", 0,
142 U64_MAX);
143 if (!prop)
144 return -ENOMEM;
145 dev->mode_config.writeback_out_fence_ptr_property = prop;
146 }
147
148 return 0;
149}
150
151static const struct drm_encoder_funcs drm_writeback_encoder_funcs = {
152 .destroy = drm_encoder_cleanup,
153};
154
155/**
156 * drm_writeback_connector_init - Initialize a writeback connector and its properties
157 * @dev: DRM device
158 * @wb_connector: Writeback connector to initialize
159 * @con_funcs: Connector funcs vtable
160 * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder
161 * @formats: Array of supported pixel formats for the writeback engine
162 * @n_formats: Length of the formats array
163 * @possible_crtcs: possible crtcs for the internal writeback encoder
164 *
165 * This function creates the writeback-connector-specific properties if they
166 * have not been already created, initializes the connector as
167 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
168 * values. It will also create an internal encoder associated with the
169 * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for
170 * the encoder helper.
171 *
172 * Drivers should always use this function instead of drm_connector_init() to
173 * set up writeback connectors.
174 *
175 * Returns: 0 on success, or a negative error code
176 */
177int drm_writeback_connector_init(struct drm_device *dev,
178 struct drm_writeback_connector *wb_connector,
179 const struct drm_connector_funcs *con_funcs,
180 const struct drm_encoder_helper_funcs *enc_helper_funcs,
181 const u32 *formats, int n_formats,
182 u32 possible_crtcs)
183{
184 int ret = 0;
185
186 drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
187
188 wb_connector->encoder.possible_crtcs = possible_crtcs;
189
190 ret = drm_encoder_init(dev, &wb_connector->encoder,
191 &drm_writeback_encoder_funcs,
192 DRM_MODE_ENCODER_VIRTUAL, NULL);
193 if (ret)
194 return ret;
195
196 ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder,
197 con_funcs, formats, n_formats);
198
199 if (ret)
200 drm_encoder_cleanup(&wb_connector->encoder);
201
202 return ret;
203}
204EXPORT_SYMBOL(drm_writeback_connector_init);
205
206static void delete_writeback_properties(struct drm_device *dev)
207{
208 if (dev->mode_config.writeback_pixel_formats_property) {
209 drm_property_destroy(dev, dev->mode_config.writeback_pixel_formats_property);
210 dev->mode_config.writeback_pixel_formats_property = NULL;
211 }
212 if (dev->mode_config.writeback_out_fence_ptr_property) {
213 drm_property_destroy(dev, dev->mode_config.writeback_out_fence_ptr_property);
214 dev->mode_config.writeback_out_fence_ptr_property = NULL;
215 }
216 if (dev->mode_config.writeback_fb_id_property) {
217 drm_property_destroy(dev, dev->mode_config.writeback_fb_id_property);
218 dev->mode_config.writeback_fb_id_property = NULL;
219 }
220}
221
222/**
223 * __drm_writeback_connector_init - Initialize a writeback connector with
224 * a custom encoder
225 *
226 * @dev: DRM device
227 * @wb_connector: Writeback connector to initialize
228 * @enc: handle to the already initialized drm encoder
229 * @formats: Array of supported pixel formats for the writeback engine
230 * @n_formats: Length of the formats array
231 *
232 * This function creates the writeback-connector-specific properties if they
233 * have not been already created, initializes the connector as
234 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
235 * values.
236 *
237 * This function assumes that the drm_writeback_connector's encoder has already been
238 * created and initialized before invoking this function.
239 *
240 * In addition, this function also assumes that callers of this API will manage
241 * assigning the encoder helper functions, possible_crtcs and any other encoder
242 * specific operation.
243 *
244 * Returns: 0 on success, or a negative error code
245 */
246static int __drm_writeback_connector_init(struct drm_device *dev,
247 struct drm_writeback_connector *wb_connector,
248 struct drm_encoder *enc, const u32 *formats,
249 int n_formats)
250{
251 struct drm_connector *connector = &wb_connector->base;
252 struct drm_mode_config *config = &dev->mode_config;
253 struct drm_property_blob *blob;
254 int ret = create_writeback_properties(dev);
255
256 if (ret != 0)
257 goto failed_properties;
258
259 connector->interlace_allowed = 0;
260
261 ret = drm_connector_attach_encoder(connector, enc);
262 if (ret)
263 goto failed_properties;
264
265 blob = drm_property_create_blob(dev, n_formats * sizeof(*formats),
266 formats);
267 if (IS_ERR(blob)) {
268 ret = PTR_ERR(blob);
269 goto failed_properties;
270 }
271
272 INIT_LIST_HEAD(&wb_connector->job_queue);
273 spin_lock_init(&wb_connector->job_lock);
274
275 wb_connector->fence_context = dma_fence_context_alloc(1);
276 spin_lock_init(&wb_connector->fence_lock);
277 snprintf(wb_connector->timeline_name,
278 sizeof(wb_connector->timeline_name),
279 "CONNECTOR:%d-%s", connector->base.id, connector->name);
280
281 drm_object_attach_property(&connector->base,
282 config->writeback_out_fence_ptr_property, 0);
283
284 drm_object_attach_property(&connector->base,
285 config->writeback_fb_id_property, 0);
286
287 drm_object_attach_property(&connector->base,
288 config->writeback_pixel_formats_property,
289 blob->base.id);
290 wb_connector->pixel_formats_blob_ptr = blob;
291
292 return 0;
293failed_properties:
294 delete_writeback_properties(dev);
295 return ret;
296}
297
298/**
299 * drm_writeback_connector_init_with_encoder - Initialize a writeback connector with
300 * a custom encoder
301 *
302 * @dev: DRM device
303 * @wb_connector: Writeback connector to initialize
304 * @enc: handle to the already initialized drm encoder
305 * @con_funcs: Connector funcs vtable
306 * @formats: Array of supported pixel formats for the writeback engine
307 * @n_formats: Length of the formats array
308 *
309 * This function creates the writeback-connector-specific properties if they
310 * have not been already created, initializes the connector as
311 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
312 * values.
313 *
314 * This function assumes that the drm_writeback_connector's encoder has already been
315 * created and initialized before invoking this function.
316 *
317 * In addition, this function also assumes that callers of this API will manage
318 * assigning the encoder helper functions, possible_crtcs and any other encoder
319 * specific operation.
320 *
321 * Drivers should always use this function instead of drm_connector_init() to
322 * set up writeback connectors if they want to manage themselves the lifetime of the
323 * associated encoder.
324 *
325 * Returns: 0 on success, or a negative error code
326 */
327int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
328 struct drm_writeback_connector *wb_connector,
329 struct drm_encoder *enc,
330 const struct drm_connector_funcs *con_funcs,
331 const u32 *formats, int n_formats)
332{
333 struct drm_connector *connector = &wb_connector->base;
334 int ret;
335
336 ret = drm_connector_init(dev, connector, con_funcs,
337 DRM_MODE_CONNECTOR_WRITEBACK);
338 if (ret)
339 return ret;
340
341 ret = __drm_writeback_connector_init(dev, wb_connector, enc, formats,
342 n_formats);
343 if (ret)
344 drm_connector_cleanup(connector);
345
346 return ret;
347}
348EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder);
349
350/**
351 * drm_writeback_connector_cleanup - Cleanup the writeback connector
352 * @dev: DRM device
353 * @data: Pointer to the writeback connector to clean up
354 *
355 * This will decrement the reference counter of blobs and destroy properties. It
356 * will also clean the remaining jobs in this writeback connector. Caution: This helper will not
357 * clean up the attached encoder and the drm_connector.
358 */
359static void drm_writeback_connector_cleanup(struct drm_device *dev,
360 void *data)
361{
362 unsigned long flags;
363 struct drm_writeback_job *pos, *n;
364 struct drm_writeback_connector *wb_connector = data;
365
366 delete_writeback_properties(dev);
367 drm_property_blob_put(wb_connector->pixel_formats_blob_ptr);
368
369 spin_lock_irqsave(&wb_connector->job_lock, flags);
370 list_for_each_entry_safe(pos, n, &wb_connector->job_queue, list_entry) {
371 list_del(&pos->list_entry);
372 drm_writeback_cleanup_job(pos);
373 }
374 spin_unlock_irqrestore(&wb_connector->job_lock, flags);
375}
376
377/**
378 * drmm_writeback_connector_init - Initialize a writeback connector with
379 * a custom encoder
380 *
381 * @dev: DRM device
382 * @wb_connector: Writeback connector to initialize
383 * @con_funcs: Connector funcs vtable
384 * @enc: Encoder to connect this writeback connector
385 * @formats: Array of supported pixel formats for the writeback engine
386 * @n_formats: Length of the formats array
387 *
388 * This function initialize a writeback connector and register its cleanup.
389 *
390 * This function creates the writeback-connector-specific properties if they
391 * have not been already created, initializes the connector as
392 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
393 * values.
394 *
395 * Returns: 0 on success, or a negative error code
396 */
397int drmm_writeback_connector_init(struct drm_device *dev,
398 struct drm_writeback_connector *wb_connector,
399 const struct drm_connector_funcs *con_funcs,
400 struct drm_encoder *enc,
401 const u32 *formats, int n_formats)
402{
403 struct drm_connector *connector = &wb_connector->base;
404 int ret;
405
406 ret = drmm_connector_init(dev, connector, con_funcs,
407 DRM_MODE_CONNECTOR_WRITEBACK, NULL);
408 if (ret)
409 return ret;
410
411 ret = __drm_writeback_connector_init(dev, wb_connector, enc, formats,
412 n_formats);
413 if (ret)
414 return ret;
415
416 ret = drmm_add_action_or_reset(dev, drm_writeback_connector_cleanup,
417 wb_connector);
418 if (ret)
419 return ret;
420
421 return 0;
422}
423EXPORT_SYMBOL(drmm_writeback_connector_init);
424
425int drm_writeback_set_fb(struct drm_connector_state *conn_state,
426 struct drm_framebuffer *fb)
427{
428 WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);
429
430 if (!conn_state->writeback_job) {
431 conn_state->writeback_job = kzalloc_obj(*conn_state->writeback_job);
432 if (!conn_state->writeback_job)
433 return -ENOMEM;
434
435 conn_state->writeback_job->connector =
436 drm_connector_to_writeback(conn_state->connector);
437 }
438
439 drm_framebuffer_assign(&conn_state->writeback_job->fb, fb);
440 return 0;
441}
442
443int drm_writeback_prepare_job(struct drm_writeback_job *job)
444{
445 struct drm_writeback_connector *connector = job->connector;
446 const struct drm_connector_helper_funcs *funcs =
447 connector->base.helper_private;
448 int ret;
449
450 if (funcs->prepare_writeback_job) {
451 ret = funcs->prepare_writeback_job(connector, job);
452 if (ret < 0)
453 return ret;
454 }
455
456 job->prepared = true;
457 return 0;
458}
459EXPORT_SYMBOL(drm_writeback_prepare_job);
460
461/**
462 * drm_writeback_queue_job - Queue a writeback job for later signalling
463 * @wb_connector: The writeback connector to queue a job on
464 * @conn_state: The connector state containing the job to queue
465 *
466 * This function adds the job contained in @conn_state to the job_queue for a
467 * writeback connector. It takes ownership of the writeback job and sets the
468 * @conn_state->writeback_job to NULL, and so no access to the job may be
469 * performed by the caller after this function returns.
470 *
471 * Drivers must ensure that for a given writeback connector, jobs are queued in
472 * exactly the same order as they will be completed by the hardware (and
473 * signaled via drm_writeback_signal_completion).
474 *
475 * For every call to drm_writeback_queue_job() there must be exactly one call to
476 * drm_writeback_signal_completion()
477 *
478 * See also: drm_writeback_signal_completion()
479 */
480void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
481 struct drm_connector_state *conn_state)
482{
483 struct drm_writeback_job *job;
484 unsigned long flags;
485
486 job = conn_state->writeback_job;
487 conn_state->writeback_job = NULL;
488
489 spin_lock_irqsave(&wb_connector->job_lock, flags);
490 list_add_tail(&job->list_entry, &wb_connector->job_queue);
491 spin_unlock_irqrestore(&wb_connector->job_lock, flags);
492}
493EXPORT_SYMBOL(drm_writeback_queue_job);
494
495void drm_writeback_cleanup_job(struct drm_writeback_job *job)
496{
497 struct drm_writeback_connector *connector = job->connector;
498 const struct drm_connector_helper_funcs *funcs =
499 connector->base.helper_private;
500
501 if (job->prepared && funcs->cleanup_writeback_job)
502 funcs->cleanup_writeback_job(connector, job);
503
504 if (job->fb)
505 drm_framebuffer_put(job->fb);
506
507 if (job->out_fence)
508 dma_fence_put(job->out_fence);
509
510 kfree(job);
511}
512EXPORT_SYMBOL(drm_writeback_cleanup_job);
513
514/*
515 * @cleanup_work: deferred cleanup of a writeback job
516 *
517 * The job cannot be cleaned up directly in drm_writeback_signal_completion,
518 * because it may be called in interrupt context. Dropping the framebuffer
519 * reference can sleep, and so the cleanup is deferred to a workqueue.
520 */
521static void cleanup_work(struct work_struct *work)
522{
523 struct drm_writeback_job *job = container_of(work,
524 struct drm_writeback_job,
525 cleanup_work);
526
527 drm_writeback_cleanup_job(job);
528}
529
530/**
531 * drm_writeback_signal_completion - Signal the completion of a writeback job
532 * @wb_connector: The writeback connector whose job is complete
533 * @status: Status code to set in the writeback out_fence (0 for success)
534 *
535 * Drivers should call this to signal the completion of a previously queued
536 * writeback job. It should be called as soon as possible after the hardware
537 * has finished writing, and may be called from interrupt context.
538 * It is the driver's responsibility to ensure that for a given connector, the
539 * hardware completes writeback jobs in the same order as they are queued.
540 *
541 * Unless the driver is holding its own reference to the framebuffer, it must
542 * not be accessed after calling this function.
543 *
544 * See also: drm_writeback_queue_job()
545 */
546void
547drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector,
548 int status)
549{
550 unsigned long flags;
551 struct drm_writeback_job *job;
552 struct dma_fence *out_fence;
553
554 spin_lock_irqsave(&wb_connector->job_lock, flags);
555 job = list_first_entry_or_null(&wb_connector->job_queue,
556 struct drm_writeback_job,
557 list_entry);
558 if (job)
559 list_del(&job->list_entry);
560
561 spin_unlock_irqrestore(&wb_connector->job_lock, flags);
562
563 if (WARN_ON(!job))
564 return;
565
566 out_fence = job->out_fence;
567 if (out_fence) {
568 if (status)
569 dma_fence_set_error(out_fence, status);
570 dma_fence_signal(out_fence);
571 dma_fence_put(out_fence);
572 job->out_fence = NULL;
573 }
574
575 INIT_WORK(&job->cleanup_work, cleanup_work);
576 queue_work(system_long_wq, &job->cleanup_work);
577}
578EXPORT_SYMBOL(drm_writeback_signal_completion);
579
580struct dma_fence *
581drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector)
582{
583 struct dma_fence *fence;
584
585 if (WARN_ON(wb_connector->base.connector_type !=
586 DRM_MODE_CONNECTOR_WRITEBACK))
587 return NULL;
588
589 fence = kzalloc_obj(*fence);
590 if (!fence)
591 return NULL;
592
593 dma_fence_init(fence, &drm_writeback_fence_ops,
594 &wb_connector->fence_lock, wb_connector->fence_context,
595 ++wb_connector->fence_seqno);
596
597 return fence;
598}
599EXPORT_SYMBOL(drm_writeback_get_out_fence);