GNU Linux-libre 5.10.219-gnu1
[releases.git] / drivers / gpu / drm / drm_writeback.c
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_modeset_helper_vtables.h>
18 #include <drm/drm_property.h>
19 #include <drm/drm_writeback.h>
20
21 /**
22  * DOC: overview
23  *
24  * Writeback connectors are used to expose hardware which can write the output
25  * from a CRTC to a memory buffer. They are used and act similarly to other
26  * types of connectors, with some important differences:
27  *
28  * * Writeback connectors don't provide a way to output visually to the user.
29  *
30  * * Writeback connectors are visible to userspace only when the client sets
31  *   DRM_CLIENT_CAP_WRITEBACK_CONNECTORS.
32  *
33  * * Writeback connectors don't have EDID.
34  *
35  * A framebuffer may only be attached to a writeback connector when the
36  * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the
37  * framebuffer applies only to a single commit (see below). A framebuffer may
38  * not be attached while the CRTC is off.
39  *
40  * Unlike with planes, when a writeback framebuffer is removed by userspace DRM
41  * makes no attempt to remove it from active use by the connector. This is
42  * because no method is provided to abort a writeback operation, and in any
43  * case making a new commit whilst a writeback is ongoing is undefined (see
44  * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished,
45  * the framebuffer will automatically no longer be in active use. As it will
46  * also have already been removed from the framebuffer list, there will be no
47  * way for any userspace application to retrieve a reference to it in the
48  * intervening period.
49  *
50  * Writeback connectors have some additional properties, which userspace
51  * can use to query and control them:
52  *
53  *  "WRITEBACK_FB_ID":
54  *      Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the
55  *      framebuffer to be written by the writeback connector. This property is
56  *      similar to the FB_ID property on planes, but will always read as zero
57  *      and is not preserved across commits.
58  *      Userspace must set this property to an output buffer every time it
59  *      wishes the buffer to get filled.
60  *
61  *  "WRITEBACK_PIXEL_FORMATS":
62  *      Immutable blob property to store the supported pixel formats table. The
63  *      data is an array of u32 DRM_FORMAT_* fourcc values.
64  *      Userspace can use this blob to find out what pixel formats are supported
65  *      by the connector's writeback engine.
66  *
67  *  "WRITEBACK_OUT_FENCE_PTR":
68  *      Userspace can use this property to provide a pointer for the kernel to
69  *      fill with a sync_file file descriptor, which will signal once the
70  *      writeback is finished. The value should be the address of a 32-bit
71  *      signed integer, cast to a u64.
72  *      Userspace should wait for this fence to signal before making another
73  *      commit affecting any of the same CRTCs, Planes or Connectors.
74  *      **Failure to do so will result in undefined behaviour.**
75  *      For this reason it is strongly recommended that all userspace
76  *      applications making use of writeback connectors *always* retrieve an
77  *      out-fence for the commit and use it appropriately.
78  *      From userspace, this property will always read as zero.
79  */
80
81 #define fence_to_wb_connector(x) container_of(x->lock, \
82                                               struct drm_writeback_connector, \
83                                               fence_lock)
84
85 static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence)
86 {
87         struct drm_writeback_connector *wb_connector =
88                 fence_to_wb_connector(fence);
89
90         return wb_connector->base.dev->driver->name;
91 }
92
93 static const char *
94 drm_writeback_fence_get_timeline_name(struct dma_fence *fence)
95 {
96         struct drm_writeback_connector *wb_connector =
97                 fence_to_wb_connector(fence);
98
99         return wb_connector->timeline_name;
100 }
101
102 static bool drm_writeback_fence_enable_signaling(struct dma_fence *fence)
103 {
104         return true;
105 }
106
107 static const struct dma_fence_ops drm_writeback_fence_ops = {
108         .get_driver_name = drm_writeback_fence_get_driver_name,
109         .get_timeline_name = drm_writeback_fence_get_timeline_name,
110         .enable_signaling = drm_writeback_fence_enable_signaling,
111 };
112
113 static int create_writeback_properties(struct drm_device *dev)
114 {
115         struct drm_property *prop;
116
117         if (!dev->mode_config.writeback_fb_id_property) {
118                 prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
119                                                   "WRITEBACK_FB_ID",
120                                                   DRM_MODE_OBJECT_FB);
121                 if (!prop)
122                         return -ENOMEM;
123                 dev->mode_config.writeback_fb_id_property = prop;
124         }
125
126         if (!dev->mode_config.writeback_pixel_formats_property) {
127                 prop = drm_property_create(dev, DRM_MODE_PROP_BLOB |
128                                            DRM_MODE_PROP_ATOMIC |
129                                            DRM_MODE_PROP_IMMUTABLE,
130                                            "WRITEBACK_PIXEL_FORMATS", 0);
131                 if (!prop)
132                         return -ENOMEM;
133                 dev->mode_config.writeback_pixel_formats_property = prop;
134         }
135
136         if (!dev->mode_config.writeback_out_fence_ptr_property) {
137                 prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
138                                                  "WRITEBACK_OUT_FENCE_PTR", 0,
139                                                  U64_MAX);
140                 if (!prop)
141                         return -ENOMEM;
142                 dev->mode_config.writeback_out_fence_ptr_property = prop;
143         }
144
145         return 0;
146 }
147
148 static const struct drm_encoder_funcs drm_writeback_encoder_funcs = {
149         .destroy = drm_encoder_cleanup,
150 };
151
152 /**
153  * drm_writeback_connector_init - Initialize a writeback connector and its properties
154  * @dev: DRM device
155  * @wb_connector: Writeback connector to initialize
156  * @con_funcs: Connector funcs vtable
157  * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder
158  * @formats: Array of supported pixel formats for the writeback engine
159  * @n_formats: Length of the formats array
160  *
161  * This function creates the writeback-connector-specific properties if they
162  * have not been already created, initializes the connector as
163  * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
164  * values. It will also create an internal encoder associated with the
165  * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for
166  * the encoder helper.
167  *
168  * Drivers should always use this function instead of drm_connector_init() to
169  * set up writeback connectors.
170  *
171  * Returns: 0 on success, or a negative error code
172  */
173 int drm_writeback_connector_init(struct drm_device *dev,
174                                  struct drm_writeback_connector *wb_connector,
175                                  const struct drm_connector_funcs *con_funcs,
176                                  const struct drm_encoder_helper_funcs *enc_helper_funcs,
177                                  const u32 *formats, int n_formats)
178 {
179         struct drm_property_blob *blob;
180         struct drm_connector *connector = &wb_connector->base;
181         struct drm_mode_config *config = &dev->mode_config;
182         int ret = create_writeback_properties(dev);
183
184         if (ret != 0)
185                 return ret;
186
187         blob = drm_property_create_blob(dev, n_formats * sizeof(*formats),
188                                         formats);
189         if (IS_ERR(blob))
190                 return PTR_ERR(blob);
191
192         drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
193         ret = drm_encoder_init(dev, &wb_connector->encoder,
194                                &drm_writeback_encoder_funcs,
195                                DRM_MODE_ENCODER_VIRTUAL, NULL);
196         if (ret)
197                 goto fail;
198
199         connector->interlace_allowed = 0;
200
201         ret = drm_connector_init(dev, connector, con_funcs,
202                                  DRM_MODE_CONNECTOR_WRITEBACK);
203         if (ret)
204                 goto connector_fail;
205
206         ret = drm_connector_attach_encoder(connector,
207                                                 &wb_connector->encoder);
208         if (ret)
209                 goto attach_fail;
210
211         INIT_LIST_HEAD(&wb_connector->job_queue);
212         spin_lock_init(&wb_connector->job_lock);
213
214         wb_connector->fence_context = dma_fence_context_alloc(1);
215         spin_lock_init(&wb_connector->fence_lock);
216         snprintf(wb_connector->timeline_name,
217                  sizeof(wb_connector->timeline_name),
218                  "CONNECTOR:%d-%s", connector->base.id, connector->name);
219
220         drm_object_attach_property(&connector->base,
221                                    config->writeback_out_fence_ptr_property, 0);
222
223         drm_object_attach_property(&connector->base,
224                                    config->writeback_fb_id_property, 0);
225
226         drm_object_attach_property(&connector->base,
227                                    config->writeback_pixel_formats_property,
228                                    blob->base.id);
229         wb_connector->pixel_formats_blob_ptr = blob;
230
231         return 0;
232
233 attach_fail:
234         drm_connector_cleanup(connector);
235 connector_fail:
236         drm_encoder_cleanup(&wb_connector->encoder);
237 fail:
238         drm_property_blob_put(blob);
239         return ret;
240 }
241 EXPORT_SYMBOL(drm_writeback_connector_init);
242
243 int drm_writeback_set_fb(struct drm_connector_state *conn_state,
244                          struct drm_framebuffer *fb)
245 {
246         WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);
247
248         if (!conn_state->writeback_job) {
249                 conn_state->writeback_job =
250                         kzalloc(sizeof(*conn_state->writeback_job), GFP_KERNEL);
251                 if (!conn_state->writeback_job)
252                         return -ENOMEM;
253
254                 conn_state->writeback_job->connector =
255                         drm_connector_to_writeback(conn_state->connector);
256         }
257
258         drm_framebuffer_assign(&conn_state->writeback_job->fb, fb);
259         return 0;
260 }
261
262 int drm_writeback_prepare_job(struct drm_writeback_job *job)
263 {
264         struct drm_writeback_connector *connector = job->connector;
265         const struct drm_connector_helper_funcs *funcs =
266                 connector->base.helper_private;
267         int ret;
268
269         if (funcs->prepare_writeback_job) {
270                 ret = funcs->prepare_writeback_job(connector, job);
271                 if (ret < 0)
272                         return ret;
273         }
274
275         job->prepared = true;
276         return 0;
277 }
278 EXPORT_SYMBOL(drm_writeback_prepare_job);
279
280 /**
281  * drm_writeback_queue_job - Queue a writeback job for later signalling
282  * @wb_connector: The writeback connector to queue a job on
283  * @conn_state: The connector state containing the job to queue
284  *
285  * This function adds the job contained in @conn_state to the job_queue for a
286  * writeback connector. It takes ownership of the writeback job and sets the
287  * @conn_state->writeback_job to NULL, and so no access to the job may be
288  * performed by the caller after this function returns.
289  *
290  * Drivers must ensure that for a given writeback connector, jobs are queued in
291  * exactly the same order as they will be completed by the hardware (and
292  * signaled via drm_writeback_signal_completion).
293  *
294  * For every call to drm_writeback_queue_job() there must be exactly one call to
295  * drm_writeback_signal_completion()
296  *
297  * See also: drm_writeback_signal_completion()
298  */
299 void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
300                              struct drm_connector_state *conn_state)
301 {
302         struct drm_writeback_job *job;
303         unsigned long flags;
304
305         job = conn_state->writeback_job;
306         conn_state->writeback_job = NULL;
307
308         spin_lock_irqsave(&wb_connector->job_lock, flags);
309         list_add_tail(&job->list_entry, &wb_connector->job_queue);
310         spin_unlock_irqrestore(&wb_connector->job_lock, flags);
311 }
312 EXPORT_SYMBOL(drm_writeback_queue_job);
313
314 void drm_writeback_cleanup_job(struct drm_writeback_job *job)
315 {
316         struct drm_writeback_connector *connector = job->connector;
317         const struct drm_connector_helper_funcs *funcs =
318                 connector->base.helper_private;
319
320         if (job->prepared && funcs->cleanup_writeback_job)
321                 funcs->cleanup_writeback_job(connector, job);
322
323         if (job->fb)
324                 drm_framebuffer_put(job->fb);
325
326         if (job->out_fence)
327                 dma_fence_put(job->out_fence);
328
329         kfree(job);
330 }
331 EXPORT_SYMBOL(drm_writeback_cleanup_job);
332
333 /*
334  * @cleanup_work: deferred cleanup of a writeback job
335  *
336  * The job cannot be cleaned up directly in drm_writeback_signal_completion,
337  * because it may be called in interrupt context. Dropping the framebuffer
338  * reference can sleep, and so the cleanup is deferred to a workqueue.
339  */
340 static void cleanup_work(struct work_struct *work)
341 {
342         struct drm_writeback_job *job = container_of(work,
343                                                      struct drm_writeback_job,
344                                                      cleanup_work);
345
346         drm_writeback_cleanup_job(job);
347 }
348
349 /**
350  * drm_writeback_signal_completion - Signal the completion of a writeback job
351  * @wb_connector: The writeback connector whose job is complete
352  * @status: Status code to set in the writeback out_fence (0 for success)
353  *
354  * Drivers should call this to signal the completion of a previously queued
355  * writeback job. It should be called as soon as possible after the hardware
356  * has finished writing, and may be called from interrupt context.
357  * It is the driver's responsibility to ensure that for a given connector, the
358  * hardware completes writeback jobs in the same order as they are queued.
359  *
360  * Unless the driver is holding its own reference to the framebuffer, it must
361  * not be accessed after calling this function.
362  *
363  * See also: drm_writeback_queue_job()
364  */
365 void
366 drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector,
367                                 int status)
368 {
369         unsigned long flags;
370         struct drm_writeback_job *job;
371         struct dma_fence *out_fence;
372
373         spin_lock_irqsave(&wb_connector->job_lock, flags);
374         job = list_first_entry_or_null(&wb_connector->job_queue,
375                                        struct drm_writeback_job,
376                                        list_entry);
377         if (job)
378                 list_del(&job->list_entry);
379
380         spin_unlock_irqrestore(&wb_connector->job_lock, flags);
381
382         if (WARN_ON(!job))
383                 return;
384
385         out_fence = job->out_fence;
386         if (out_fence) {
387                 if (status)
388                         dma_fence_set_error(out_fence, status);
389                 dma_fence_signal(out_fence);
390                 dma_fence_put(out_fence);
391                 job->out_fence = NULL;
392         }
393
394         INIT_WORK(&job->cleanup_work, cleanup_work);
395         queue_work(system_long_wq, &job->cleanup_work);
396 }
397 EXPORT_SYMBOL(drm_writeback_signal_completion);
398
399 struct dma_fence *
400 drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector)
401 {
402         struct dma_fence *fence;
403
404         if (WARN_ON(wb_connector->base.connector_type !=
405                     DRM_MODE_CONNECTOR_WRITEBACK))
406                 return NULL;
407
408         fence = kzalloc(sizeof(*fence), GFP_KERNEL);
409         if (!fence)
410                 return NULL;
411
412         dma_fence_init(fence, &drm_writeback_fence_ops,
413                        &wb_connector->fence_lock, wb_connector->fence_context,
414                        ++wb_connector->fence_seqno);
415
416         return fence;
417 }
418 EXPORT_SYMBOL(drm_writeback_get_out_fence);