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); 419