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 86static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence) 87{ 88 struct drm_writeback_connector *wb_connector = 89 fence_to_wb_connector(fence); 90 91 return wb_connector->base.dev->driver->name; 92} 93 94static const char * 95drm_writeback_fence_get_timeline_name(struct dma_fence *fence) 96{ 97 struct drm_writeback_connector *wb_connector = 98 fence_to_wb_connector(fence); 99 100 return wb_connector->timeline_name; 101} 102 103static bool drm_writeback_fence_enable_signaling(struct dma_fence *fence) 104{ 105 return true; 106} 107 108static 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 114static int create_writeback_properties(struct drm_device *dev) 115{ 116 struct drm_property *prop; 117 118 if (!dev->mode_config.writeback_fb_id_property) { 119 prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC, 120 "WRITEBACK_FB_ID", 121 DRM_MODE_OBJECT_FB); 122 if (!prop) 123 return -ENOMEM; 124 dev->mode_config.writeback_fb_id_property = prop; 125 } 126 127 if (!dev->mode_config.writeback_pixel_formats_property) { 128 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 if (!prop) 133 return -ENOMEM; 134 dev->mode_config.writeback_pixel_formats_property = prop; 135 } 136 137 if (!dev->mode_config.writeback_out_fence_ptr_property) { 138 prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC, 139 "WRITEBACK_OUT_FENCE_PTR", 0, 140 U64_MAX); 141 if (!prop) 142 return -ENOMEM; 143 dev->mode_config.writeback_out_fence_ptr_property = prop; 144 } 145 146 return 0; 147} 148 149static 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 */ 175int 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 int ret = 0; 183 184 drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); 185 186 wb_connector->encoder.possible_crtcs = possible_crtcs; 187 188 ret = drm_encoder_init(dev, &wb_connector->encoder, 189 &drm_writeback_encoder_funcs, 190 DRM_MODE_ENCODER_VIRTUAL, NULL); 191 if (ret) 192 return ret; 193 194 ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder, 195 con_funcs, formats, n_formats); 196 197 if (ret) 198 drm_encoder_cleanup(&wb_connector->encoder); 199 200 return ret; 201} 202EXPORT_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 */ 233int 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 struct drm_connector *connector = &wb_connector->base; 240 struct drm_mode_config *config = &dev->mode_config; 241 int ret = create_writeback_properties(dev); 242 243 if (ret != 0) 244 return ret; 245 246 blob = drm_property_create_blob(dev, n_formats * sizeof(*formats), 247 formats); 248 if (IS_ERR(blob)) 249 return PTR_ERR(blob); 250 251 252 connector->interlace_allowed = 0; 253 254 ret = drm_connector_init(dev, connector, con_funcs, 255 DRM_MODE_CONNECTOR_WRITEBACK); 256 if (ret) 257 goto connector_fail; 258 259 ret = drm_connector_attach_encoder(connector, enc); 260 if (ret) 261 goto attach_fail; 262 263 INIT_LIST_HEAD(&wb_connector->job_queue); 264 spin_lock_init(&wb_connector->job_lock); 265 266 wb_connector->fence_context = dma_fence_context_alloc(1); 267 spin_lock_init(&wb_connector->fence_lock); 268 snprintf(wb_connector->timeline_name, 269 sizeof(wb_connector->timeline_name), 270 "CONNECTOR:%d-%s", connector->base.id, connector->name); 271 272 drm_object_attach_property(&connector->base, 273 config->writeback_out_fence_ptr_property, 0); 274 275 drm_object_attach_property(&connector->base, 276 config->writeback_fb_id_property, 0); 277 278 drm_object_attach_property(&connector->base, 279 config->writeback_pixel_formats_property, 280 blob->base.id); 281 wb_connector->pixel_formats_blob_ptr = blob; 282 283 return 0; 284 285attach_fail: 286 drm_connector_cleanup(connector); 287connector_fail: 288 drm_property_blob_put(blob); 289 return ret; 290} 291EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder); 292 293int drm_writeback_set_fb(struct drm_connector_state *conn_state, 294 struct drm_framebuffer *fb) 295{ 296 WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK); 297 298 if (!conn_state->writeback_job) { 299 conn_state->writeback_job = 300 kzalloc(sizeof(*conn_state->writeback_job), GFP_KERNEL); 301 if (!conn_state->writeback_job) 302 return -ENOMEM; 303 304 conn_state->writeback_job->connector = 305 drm_connector_to_writeback(conn_state->connector); 306 } 307 308 drm_framebuffer_assign(&conn_state->writeback_job->fb, fb); 309 return 0; 310} 311 312int drm_writeback_prepare_job(struct drm_writeback_job *job) 313{ 314 struct drm_writeback_connector *connector = job->connector; 315 const struct drm_connector_helper_funcs *funcs = 316 connector->base.helper_private; 317 int ret; 318 319 if (funcs->prepare_writeback_job) { 320 ret = funcs->prepare_writeback_job(connector, job); 321 if (ret < 0) 322 return ret; 323 } 324 325 job->prepared = true; 326 return 0; 327} 328EXPORT_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 */ 349void 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 job = conn_state->writeback_job; 356 conn_state->writeback_job = NULL; 357 358 spin_lock_irqsave(&wb_connector->job_lock, flags); 359 list_add_tail(&job->list_entry, &wb_connector->job_queue); 360 spin_unlock_irqrestore(&wb_connector->job_lock, flags); 361} 362EXPORT_SYMBOL(drm_writeback_queue_job); 363 364void drm_writeback_cleanup_job(struct drm_writeback_job *job) 365{ 366 struct drm_writeback_connector *connector = job->connector; 367 const struct drm_connector_helper_funcs *funcs = 368 connector->base.helper_private; 369 370 if (job->prepared && funcs->cleanup_writeback_job) 371 funcs->cleanup_writeback_job(connector, job); 372 373 if (job->fb) 374 drm_framebuffer_put(job->fb); 375 376 if (job->out_fence) 377 dma_fence_put(job->out_fence); 378 379 kfree(job); 380} 381EXPORT_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 */ 390static void cleanup_work(struct work_struct *work) 391{ 392 struct drm_writeback_job *job = container_of(work, 393 struct drm_writeback_job, 394 cleanup_work); 395 396 drm_writeback_cleanup_job(job); 397} 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 */ 415void 416drm_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 spin_lock_irqsave(&wb_connector->job_lock, flags); 424 job = list_first_entry_or_null(&wb_connector->job_queue, 425 struct drm_writeback_job, 426 list_entry); 427 if (job) 428 list_del(&job->list_entry); 429 430 spin_unlock_irqrestore(&wb_connector->job_lock, flags); 431 432 if (WARN_ON(!job)) 433 return; 434 435 out_fence = job->out_fence; 436 if (out_fence) { 437 if (status) 438 dma_fence_set_error(out_fence, status); 439 dma_fence_signal(out_fence); 440 dma_fence_put(out_fence); 441 job->out_fence = NULL; 442 } 443 444 INIT_WORK(&job->cleanup_work, cleanup_work); 445 queue_work(system_long_wq, &job->cleanup_work); 446} 447EXPORT_SYMBOL(drm_writeback_signal_completion); 448 449struct dma_fence * 450drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector) 451{ 452 struct dma_fence *fence; 453 454 if (WARN_ON(wb_connector->base.connector_type != 455 DRM_MODE_CONNECTOR_WRITEBACK)) 456 return NULL; 457 458 fence = kzalloc(sizeof(*fence), GFP_KERNEL); 459 if (!fence) 460 return NULL; 461 462 dma_fence_init(fence, &drm_writeback_fence_ops, 463 &wb_connector->fence_lock, wb_connector->fence_context, 464 ++wb_connector->fence_seqno); 465 466 return fence; 467} 468EXPORT_SYMBOL(drm_writeback_get_out_fence); 469