1935774cdSBrian Starkey // SPDX-License-Identifier: GPL-2.0 2935774cdSBrian Starkey /* 3935774cdSBrian Starkey * (C) COPYRIGHT 2016 ARM Limited. All rights reserved. 4935774cdSBrian Starkey * Author: Brian Starkey <brian.starkey@arm.com> 5935774cdSBrian Starkey * 6935774cdSBrian Starkey * This program is free software and is provided to you under the terms of the 7935774cdSBrian Starkey * GNU General Public License version 2 as published by the Free Software 8935774cdSBrian Starkey * Foundation, and any use by you of this program is subject to the terms 9935774cdSBrian Starkey * of such GNU licence. 10935774cdSBrian Starkey */ 11935774cdSBrian Starkey 12935774cdSBrian Starkey #include <drm/drm_crtc.h> 13935774cdSBrian Starkey #include <drm/drm_modeset_helper_vtables.h> 14935774cdSBrian Starkey #include <drm/drm_property.h> 15935774cdSBrian Starkey #include <drm/drm_writeback.h> 16935774cdSBrian Starkey #include <drm/drmP.h> 17b13cc8ddSBrian Starkey #include <linux/dma-fence.h> 18935774cdSBrian Starkey 19935774cdSBrian Starkey /** 20935774cdSBrian Starkey * DOC: overview 21935774cdSBrian Starkey * 22935774cdSBrian Starkey * Writeback connectors are used to expose hardware which can write the output 23935774cdSBrian Starkey * from a CRTC to a memory buffer. They are used and act similarly to other 24935774cdSBrian Starkey * types of connectors, with some important differences: 2573915b2bSBoris Brezillon * 2673915b2bSBoris Brezillon * * Writeback connectors don't provide a way to output visually to the user. 2773915b2bSBoris Brezillon * 2873915b2bSBoris Brezillon * * Writeback connectors should always report as "disconnected" (so that 29935774cdSBrian Starkey * clients which don't understand them will ignore them). 3073915b2bSBoris Brezillon * 3173915b2bSBoris Brezillon * * Writeback connectors don't have EDID. 32935774cdSBrian Starkey * 33935774cdSBrian Starkey * A framebuffer may only be attached to a writeback connector when the 34935774cdSBrian Starkey * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the 35935774cdSBrian Starkey * framebuffer applies only to a single commit (see below). A framebuffer may 36935774cdSBrian Starkey * not be attached while the CRTC is off. 37935774cdSBrian Starkey * 38b13cc8ddSBrian Starkey * Unlike with planes, when a writeback framebuffer is removed by userspace DRM 39b13cc8ddSBrian Starkey * makes no attempt to remove it from active use by the connector. This is 40b13cc8ddSBrian Starkey * because no method is provided to abort a writeback operation, and in any 41b13cc8ddSBrian Starkey * case making a new commit whilst a writeback is ongoing is undefined (see 42b13cc8ddSBrian Starkey * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished, 43b13cc8ddSBrian Starkey * the framebuffer will automatically no longer be in active use. As it will 44b13cc8ddSBrian Starkey * also have already been removed from the framebuffer list, there will be no 45b13cc8ddSBrian Starkey * way for any userspace application to retrieve a reference to it in the 46b13cc8ddSBrian Starkey * intervening period. 47b13cc8ddSBrian Starkey * 48935774cdSBrian Starkey * Writeback connectors have some additional properties, which userspace 49935774cdSBrian Starkey * can use to query and control them: 50935774cdSBrian Starkey * 51935774cdSBrian Starkey * "WRITEBACK_FB_ID": 52935774cdSBrian Starkey * Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the 53935774cdSBrian Starkey * framebuffer to be written by the writeback connector. This property is 54935774cdSBrian Starkey * similar to the FB_ID property on planes, but will always read as zero 55935774cdSBrian Starkey * and is not preserved across commits. 56935774cdSBrian Starkey * Userspace must set this property to an output buffer every time it 57935774cdSBrian Starkey * wishes the buffer to get filled. 58935774cdSBrian Starkey * 59935774cdSBrian Starkey * "WRITEBACK_PIXEL_FORMATS": 60935774cdSBrian Starkey * Immutable blob property to store the supported pixel formats table. The 61935774cdSBrian Starkey * data is an array of u32 DRM_FORMAT_* fourcc values. 62935774cdSBrian Starkey * Userspace can use this blob to find out what pixel formats are supported 63935774cdSBrian Starkey * by the connector's writeback engine. 64b13cc8ddSBrian Starkey * 65b13cc8ddSBrian Starkey * "WRITEBACK_OUT_FENCE_PTR": 66b13cc8ddSBrian Starkey * Userspace can use this property to provide a pointer for the kernel to 67b13cc8ddSBrian Starkey * fill with a sync_file file descriptor, which will signal once the 68b13cc8ddSBrian Starkey * writeback is finished. The value should be the address of a 32-bit 69b13cc8ddSBrian Starkey * signed integer, cast to a u64. 70b13cc8ddSBrian Starkey * Userspace should wait for this fence to signal before making another 71b13cc8ddSBrian Starkey * commit affecting any of the same CRTCs, Planes or Connectors. 72b13cc8ddSBrian Starkey * **Failure to do so will result in undefined behaviour.** 73b13cc8ddSBrian Starkey * For this reason it is strongly recommended that all userspace 74b13cc8ddSBrian Starkey * applications making use of writeback connectors *always* retrieve an 75b13cc8ddSBrian Starkey * out-fence for the commit and use it appropriately. 76b13cc8ddSBrian Starkey * From userspace, this property will always read as zero. 77935774cdSBrian Starkey */ 78935774cdSBrian Starkey 79b13cc8ddSBrian Starkey #define fence_to_wb_connector(x) container_of(x->lock, \ 80b13cc8ddSBrian Starkey struct drm_writeback_connector, \ 81b13cc8ddSBrian Starkey fence_lock) 82b13cc8ddSBrian Starkey 83b13cc8ddSBrian Starkey static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence) 84b13cc8ddSBrian Starkey { 85b13cc8ddSBrian Starkey struct drm_writeback_connector *wb_connector = 86b13cc8ddSBrian Starkey fence_to_wb_connector(fence); 87b13cc8ddSBrian Starkey 88b13cc8ddSBrian Starkey return wb_connector->base.dev->driver->name; 89b13cc8ddSBrian Starkey } 90b13cc8ddSBrian Starkey 91b13cc8ddSBrian Starkey static const char * 92b13cc8ddSBrian Starkey drm_writeback_fence_get_timeline_name(struct dma_fence *fence) 93b13cc8ddSBrian Starkey { 94b13cc8ddSBrian Starkey struct drm_writeback_connector *wb_connector = 95b13cc8ddSBrian Starkey fence_to_wb_connector(fence); 96b13cc8ddSBrian Starkey 97b13cc8ddSBrian Starkey return wb_connector->timeline_name; 98b13cc8ddSBrian Starkey } 99b13cc8ddSBrian Starkey 100b13cc8ddSBrian Starkey static bool drm_writeback_fence_enable_signaling(struct dma_fence *fence) 101b13cc8ddSBrian Starkey { 102b13cc8ddSBrian Starkey return true; 103b13cc8ddSBrian Starkey } 104b13cc8ddSBrian Starkey 105b13cc8ddSBrian Starkey static const struct dma_fence_ops drm_writeback_fence_ops = { 106b13cc8ddSBrian Starkey .get_driver_name = drm_writeback_fence_get_driver_name, 107b13cc8ddSBrian Starkey .get_timeline_name = drm_writeback_fence_get_timeline_name, 108b13cc8ddSBrian Starkey .enable_signaling = drm_writeback_fence_enable_signaling, 109b13cc8ddSBrian Starkey .wait = dma_fence_default_wait, 110b13cc8ddSBrian Starkey }; 111b13cc8ddSBrian Starkey 112935774cdSBrian Starkey static int create_writeback_properties(struct drm_device *dev) 113935774cdSBrian Starkey { 114935774cdSBrian Starkey struct drm_property *prop; 115935774cdSBrian Starkey 116935774cdSBrian Starkey if (!dev->mode_config.writeback_fb_id_property) { 117935774cdSBrian Starkey prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC, 118935774cdSBrian Starkey "WRITEBACK_FB_ID", 119935774cdSBrian Starkey DRM_MODE_OBJECT_FB); 120935774cdSBrian Starkey if (!prop) 121935774cdSBrian Starkey return -ENOMEM; 122935774cdSBrian Starkey dev->mode_config.writeback_fb_id_property = prop; 123935774cdSBrian Starkey } 124935774cdSBrian Starkey 125935774cdSBrian Starkey if (!dev->mode_config.writeback_pixel_formats_property) { 126935774cdSBrian Starkey prop = drm_property_create(dev, DRM_MODE_PROP_BLOB | 127935774cdSBrian Starkey DRM_MODE_PROP_ATOMIC | 128935774cdSBrian Starkey DRM_MODE_PROP_IMMUTABLE, 129935774cdSBrian Starkey "WRITEBACK_PIXEL_FORMATS", 0); 130935774cdSBrian Starkey if (!prop) 131935774cdSBrian Starkey return -ENOMEM; 132935774cdSBrian Starkey dev->mode_config.writeback_pixel_formats_property = prop; 133935774cdSBrian Starkey } 134935774cdSBrian Starkey 135b13cc8ddSBrian Starkey if (!dev->mode_config.writeback_out_fence_ptr_property) { 136b13cc8ddSBrian Starkey prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC, 137b13cc8ddSBrian Starkey "WRITEBACK_OUT_FENCE_PTR", 0, 138b13cc8ddSBrian Starkey U64_MAX); 139b13cc8ddSBrian Starkey if (!prop) 140b13cc8ddSBrian Starkey return -ENOMEM; 141b13cc8ddSBrian Starkey dev->mode_config.writeback_out_fence_ptr_property = prop; 142b13cc8ddSBrian Starkey } 143b13cc8ddSBrian Starkey 144935774cdSBrian Starkey return 0; 145935774cdSBrian Starkey } 146935774cdSBrian Starkey 147935774cdSBrian Starkey static const struct drm_encoder_funcs drm_writeback_encoder_funcs = { 148935774cdSBrian Starkey .destroy = drm_encoder_cleanup, 149935774cdSBrian Starkey }; 150935774cdSBrian Starkey 151935774cdSBrian Starkey /** 152935774cdSBrian Starkey * drm_writeback_connector_init - Initialize a writeback connector and its properties 153935774cdSBrian Starkey * @dev: DRM device 154935774cdSBrian Starkey * @wb_connector: Writeback connector to initialize 155935774cdSBrian Starkey * @con_funcs: Connector funcs vtable 156935774cdSBrian Starkey * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder 157935774cdSBrian Starkey * @formats: Array of supported pixel formats for the writeback engine 158935774cdSBrian Starkey * @n_formats: Length of the formats array 159935774cdSBrian Starkey * 160935774cdSBrian Starkey * This function creates the writeback-connector-specific properties if they 161935774cdSBrian Starkey * have not been already created, initializes the connector as 162935774cdSBrian Starkey * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property 163935774cdSBrian Starkey * values. It will also create an internal encoder associated with the 164935774cdSBrian Starkey * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for 165935774cdSBrian Starkey * the encoder helper. 166935774cdSBrian Starkey * 167935774cdSBrian Starkey * Drivers should always use this function instead of drm_connector_init() to 168935774cdSBrian Starkey * set up writeback connectors. 169935774cdSBrian Starkey * 170935774cdSBrian Starkey * Returns: 0 on success, or a negative error code 171935774cdSBrian Starkey */ 172935774cdSBrian Starkey int drm_writeback_connector_init(struct drm_device *dev, 173935774cdSBrian Starkey struct drm_writeback_connector *wb_connector, 174935774cdSBrian Starkey const struct drm_connector_funcs *con_funcs, 175935774cdSBrian Starkey const struct drm_encoder_helper_funcs *enc_helper_funcs, 176935774cdSBrian Starkey const u32 *formats, int n_formats) 177935774cdSBrian Starkey { 178935774cdSBrian Starkey struct drm_property_blob *blob; 179935774cdSBrian Starkey struct drm_connector *connector = &wb_connector->base; 180935774cdSBrian Starkey struct drm_mode_config *config = &dev->mode_config; 181935774cdSBrian Starkey int ret = create_writeback_properties(dev); 182935774cdSBrian Starkey 183935774cdSBrian Starkey if (ret != 0) 184935774cdSBrian Starkey return ret; 185935774cdSBrian Starkey 186935774cdSBrian Starkey blob = drm_property_create_blob(dev, n_formats * sizeof(*formats), 187935774cdSBrian Starkey formats); 188935774cdSBrian Starkey if (IS_ERR(blob)) 189935774cdSBrian Starkey return PTR_ERR(blob); 190935774cdSBrian Starkey 191935774cdSBrian Starkey drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); 192935774cdSBrian Starkey ret = drm_encoder_init(dev, &wb_connector->encoder, 193935774cdSBrian Starkey &drm_writeback_encoder_funcs, 194935774cdSBrian Starkey DRM_MODE_ENCODER_VIRTUAL, NULL); 195935774cdSBrian Starkey if (ret) 196935774cdSBrian Starkey goto fail; 197935774cdSBrian Starkey 198935774cdSBrian Starkey connector->interlace_allowed = 0; 199935774cdSBrian Starkey 200935774cdSBrian Starkey ret = drm_connector_init(dev, connector, con_funcs, 201935774cdSBrian Starkey DRM_MODE_CONNECTOR_WRITEBACK); 202935774cdSBrian Starkey if (ret) 203935774cdSBrian Starkey goto connector_fail; 204935774cdSBrian Starkey 205*cde4c44dSDaniel Vetter ret = drm_connector_attach_encoder(connector, 206935774cdSBrian Starkey &wb_connector->encoder); 207935774cdSBrian Starkey if (ret) 208935774cdSBrian Starkey goto attach_fail; 209935774cdSBrian Starkey 210935774cdSBrian Starkey INIT_LIST_HEAD(&wb_connector->job_queue); 211935774cdSBrian Starkey spin_lock_init(&wb_connector->job_lock); 212935774cdSBrian Starkey 213b13cc8ddSBrian Starkey wb_connector->fence_context = dma_fence_context_alloc(1); 214b13cc8ddSBrian Starkey spin_lock_init(&wb_connector->fence_lock); 215b13cc8ddSBrian Starkey snprintf(wb_connector->timeline_name, 216b13cc8ddSBrian Starkey sizeof(wb_connector->timeline_name), 217b13cc8ddSBrian Starkey "CONNECTOR:%d-%s", connector->base.id, connector->name); 218b13cc8ddSBrian Starkey 219b13cc8ddSBrian Starkey drm_object_attach_property(&connector->base, 220b13cc8ddSBrian Starkey config->writeback_out_fence_ptr_property, 0); 221b13cc8ddSBrian Starkey 222935774cdSBrian Starkey drm_object_attach_property(&connector->base, 223935774cdSBrian Starkey config->writeback_fb_id_property, 0); 224935774cdSBrian Starkey 225935774cdSBrian Starkey drm_object_attach_property(&connector->base, 226935774cdSBrian Starkey config->writeback_pixel_formats_property, 227935774cdSBrian Starkey blob->base.id); 228935774cdSBrian Starkey wb_connector->pixel_formats_blob_ptr = blob; 229935774cdSBrian Starkey 230935774cdSBrian Starkey return 0; 231935774cdSBrian Starkey 232935774cdSBrian Starkey attach_fail: 233935774cdSBrian Starkey drm_connector_cleanup(connector); 234935774cdSBrian Starkey connector_fail: 235935774cdSBrian Starkey drm_encoder_cleanup(&wb_connector->encoder); 236935774cdSBrian Starkey fail: 237935774cdSBrian Starkey drm_property_blob_put(blob); 238935774cdSBrian Starkey return ret; 239935774cdSBrian Starkey } 240935774cdSBrian Starkey EXPORT_SYMBOL(drm_writeback_connector_init); 241935774cdSBrian Starkey 242935774cdSBrian Starkey /** 243935774cdSBrian Starkey * drm_writeback_queue_job - Queue a writeback job for later signalling 244935774cdSBrian Starkey * @wb_connector: The writeback connector to queue a job on 245935774cdSBrian Starkey * @job: The job to queue 246935774cdSBrian Starkey * 247935774cdSBrian Starkey * This function adds a job to the job_queue for a writeback connector. It 248935774cdSBrian Starkey * should be considered to take ownership of the writeback job, and so any other 249935774cdSBrian Starkey * references to the job must be cleared after calling this function. 250935774cdSBrian Starkey * 251935774cdSBrian Starkey * Drivers must ensure that for a given writeback connector, jobs are queued in 252935774cdSBrian Starkey * exactly the same order as they will be completed by the hardware (and 253935774cdSBrian Starkey * signaled via drm_writeback_signal_completion). 254935774cdSBrian Starkey * 255935774cdSBrian Starkey * For every call to drm_writeback_queue_job() there must be exactly one call to 256935774cdSBrian Starkey * drm_writeback_signal_completion() 257935774cdSBrian Starkey * 258935774cdSBrian Starkey * See also: drm_writeback_signal_completion() 259935774cdSBrian Starkey */ 260935774cdSBrian Starkey void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector, 261935774cdSBrian Starkey struct drm_writeback_job *job) 262935774cdSBrian Starkey { 263935774cdSBrian Starkey unsigned long flags; 264935774cdSBrian Starkey 265935774cdSBrian Starkey spin_lock_irqsave(&wb_connector->job_lock, flags); 266935774cdSBrian Starkey list_add_tail(&job->list_entry, &wb_connector->job_queue); 267935774cdSBrian Starkey spin_unlock_irqrestore(&wb_connector->job_lock, flags); 268935774cdSBrian Starkey } 269935774cdSBrian Starkey EXPORT_SYMBOL(drm_writeback_queue_job); 270935774cdSBrian Starkey 271935774cdSBrian Starkey /* 272935774cdSBrian Starkey * @cleanup_work: deferred cleanup of a writeback job 273935774cdSBrian Starkey * 274935774cdSBrian Starkey * The job cannot be cleaned up directly in drm_writeback_signal_completion, 275935774cdSBrian Starkey * because it may be called in interrupt context. Dropping the framebuffer 276935774cdSBrian Starkey * reference can sleep, and so the cleanup is deferred to a workqueue. 277935774cdSBrian Starkey */ 278935774cdSBrian Starkey static void cleanup_work(struct work_struct *work) 279935774cdSBrian Starkey { 280935774cdSBrian Starkey struct drm_writeback_job *job = container_of(work, 281935774cdSBrian Starkey struct drm_writeback_job, 282935774cdSBrian Starkey cleanup_work); 283935774cdSBrian Starkey drm_framebuffer_put(job->fb); 284935774cdSBrian Starkey kfree(job); 285935774cdSBrian Starkey } 286935774cdSBrian Starkey 287935774cdSBrian Starkey 288935774cdSBrian Starkey /** 289935774cdSBrian Starkey * drm_writeback_signal_completion - Signal the completion of a writeback job 290935774cdSBrian Starkey * @wb_connector: The writeback connector whose job is complete 291b13cc8ddSBrian Starkey * @status: Status code to set in the writeback out_fence (0 for success) 292935774cdSBrian Starkey * 293935774cdSBrian Starkey * Drivers should call this to signal the completion of a previously queued 294935774cdSBrian Starkey * writeback job. It should be called as soon as possible after the hardware 295935774cdSBrian Starkey * has finished writing, and may be called from interrupt context. 296935774cdSBrian Starkey * It is the driver's responsibility to ensure that for a given connector, the 297935774cdSBrian Starkey * hardware completes writeback jobs in the same order as they are queued. 298935774cdSBrian Starkey * 299935774cdSBrian Starkey * Unless the driver is holding its own reference to the framebuffer, it must 300935774cdSBrian Starkey * not be accessed after calling this function. 301935774cdSBrian Starkey * 302935774cdSBrian Starkey * See also: drm_writeback_queue_job() 303935774cdSBrian Starkey */ 304935774cdSBrian Starkey void 305b13cc8ddSBrian Starkey drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector, 306b13cc8ddSBrian Starkey int status) 307935774cdSBrian Starkey { 308935774cdSBrian Starkey unsigned long flags; 309935774cdSBrian Starkey struct drm_writeback_job *job; 310935774cdSBrian Starkey 311935774cdSBrian Starkey spin_lock_irqsave(&wb_connector->job_lock, flags); 312935774cdSBrian Starkey job = list_first_entry_or_null(&wb_connector->job_queue, 313935774cdSBrian Starkey struct drm_writeback_job, 314935774cdSBrian Starkey list_entry); 315b13cc8ddSBrian Starkey if (job) { 316935774cdSBrian Starkey list_del(&job->list_entry); 317b13cc8ddSBrian Starkey if (job->out_fence) { 318b13cc8ddSBrian Starkey if (status) 319b13cc8ddSBrian Starkey dma_fence_set_error(job->out_fence, status); 320b13cc8ddSBrian Starkey dma_fence_signal(job->out_fence); 321b13cc8ddSBrian Starkey dma_fence_put(job->out_fence); 322b13cc8ddSBrian Starkey } 323b13cc8ddSBrian Starkey } 324935774cdSBrian Starkey spin_unlock_irqrestore(&wb_connector->job_lock, flags); 325935774cdSBrian Starkey 326935774cdSBrian Starkey if (WARN_ON(!job)) 327935774cdSBrian Starkey return; 328935774cdSBrian Starkey 329935774cdSBrian Starkey INIT_WORK(&job->cleanup_work, cleanup_work); 330935774cdSBrian Starkey queue_work(system_long_wq, &job->cleanup_work); 331935774cdSBrian Starkey } 332935774cdSBrian Starkey EXPORT_SYMBOL(drm_writeback_signal_completion); 333b13cc8ddSBrian Starkey 334b13cc8ddSBrian Starkey struct dma_fence * 335b13cc8ddSBrian Starkey drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector) 336b13cc8ddSBrian Starkey { 337b13cc8ddSBrian Starkey struct dma_fence *fence; 338b13cc8ddSBrian Starkey 339b13cc8ddSBrian Starkey if (WARN_ON(wb_connector->base.connector_type != 340b13cc8ddSBrian Starkey DRM_MODE_CONNECTOR_WRITEBACK)) 341b13cc8ddSBrian Starkey return NULL; 342b13cc8ddSBrian Starkey 343b13cc8ddSBrian Starkey fence = kzalloc(sizeof(*fence), GFP_KERNEL); 344b13cc8ddSBrian Starkey if (!fence) 345b13cc8ddSBrian Starkey return NULL; 346b13cc8ddSBrian Starkey 347b13cc8ddSBrian Starkey dma_fence_init(fence, &drm_writeback_fence_ops, 348b13cc8ddSBrian Starkey &wb_connector->fence_lock, wb_connector->fence_context, 349b13cc8ddSBrian Starkey ++wb_connector->fence_seqno); 350b13cc8ddSBrian Starkey 351b13cc8ddSBrian Starkey return fence; 352b13cc8ddSBrian Starkey } 353b13cc8ddSBrian Starkey EXPORT_SYMBOL(drm_writeback_get_out_fence); 354