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