// SPDX-License-Identifier: GPL-2.0 /* * (C) COPYRIGHT 2016 ARM Limited. All rights reserved. * Author: Brian Starkey * * This program is free software and is provided to you under the terms of the * GNU General Public License version 2 as published by the Free Software * Foundation, and any use by you of this program is subject to the terms * of such GNU licence. */ #include #include #include #include #include /** * DOC: overview * * Writeback connectors are used to expose hardware which can write the output * from a CRTC to a memory buffer. They are used and act similarly to other * types of connectors, with some important differences: * - Writeback connectors don't provide a way to output visually to the user. * - Writeback connectors should always report as "disconnected" (so that * clients which don't understand them will ignore them). * - Writeback connectors don't have EDID. * * A framebuffer may only be attached to a writeback connector when the * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the * framebuffer applies only to a single commit (see below). A framebuffer may * not be attached while the CRTC is off. * * Writeback connectors have some additional properties, which userspace * can use to query and control them: * * "WRITEBACK_FB_ID": * Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the * framebuffer to be written by the writeback connector. This property is * similar to the FB_ID property on planes, but will always read as zero * and is not preserved across commits. * Userspace must set this property to an output buffer every time it * wishes the buffer to get filled. * * "WRITEBACK_PIXEL_FORMATS": * Immutable blob property to store the supported pixel formats table. The * data is an array of u32 DRM_FORMAT_* fourcc values. * Userspace can use this blob to find out what pixel formats are supported * by the connector's writeback engine. */ static int create_writeback_properties(struct drm_device *dev) { struct drm_property *prop; if (!dev->mode_config.writeback_fb_id_property) { prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC, "WRITEBACK_FB_ID", DRM_MODE_OBJECT_FB); if (!prop) return -ENOMEM; dev->mode_config.writeback_fb_id_property = prop; } if (!dev->mode_config.writeback_pixel_formats_property) { prop = drm_property_create(dev, DRM_MODE_PROP_BLOB | DRM_MODE_PROP_ATOMIC | DRM_MODE_PROP_IMMUTABLE, "WRITEBACK_PIXEL_FORMATS", 0); if (!prop) return -ENOMEM; dev->mode_config.writeback_pixel_formats_property = prop; } return 0; } static const struct drm_encoder_funcs drm_writeback_encoder_funcs = { .destroy = drm_encoder_cleanup, }; /** * drm_writeback_connector_init - Initialize a writeback connector and its properties * @dev: DRM device * @wb_connector: Writeback connector to initialize * @con_funcs: Connector funcs vtable * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder * @formats: Array of supported pixel formats for the writeback engine * @n_formats: Length of the formats array * * This function creates the writeback-connector-specific properties if they * have not been already created, initializes the connector as * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property * values. It will also create an internal encoder associated with the * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for * the encoder helper. * * Drivers should always use this function instead of drm_connector_init() to * set up writeback connectors. * * Returns: 0 on success, or a negative error code */ int drm_writeback_connector_init(struct drm_device *dev, struct drm_writeback_connector *wb_connector, const struct drm_connector_funcs *con_funcs, const struct drm_encoder_helper_funcs *enc_helper_funcs, const u32 *formats, int n_formats) { struct drm_property_blob *blob; struct drm_connector *connector = &wb_connector->base; struct drm_mode_config *config = &dev->mode_config; int ret = create_writeback_properties(dev); if (ret != 0) return ret; blob = drm_property_create_blob(dev, n_formats * sizeof(*formats), formats); if (IS_ERR(blob)) return PTR_ERR(blob); drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); ret = drm_encoder_init(dev, &wb_connector->encoder, &drm_writeback_encoder_funcs, DRM_MODE_ENCODER_VIRTUAL, NULL); if (ret) goto fail; connector->interlace_allowed = 0; ret = drm_connector_init(dev, connector, con_funcs, DRM_MODE_CONNECTOR_WRITEBACK); if (ret) goto connector_fail; ret = drm_mode_connector_attach_encoder(connector, &wb_connector->encoder); if (ret) goto attach_fail; INIT_LIST_HEAD(&wb_connector->job_queue); spin_lock_init(&wb_connector->job_lock); drm_object_attach_property(&connector->base, config->writeback_fb_id_property, 0); drm_object_attach_property(&connector->base, config->writeback_pixel_formats_property, blob->base.id); wb_connector->pixel_formats_blob_ptr = blob; return 0; attach_fail: drm_connector_cleanup(connector); connector_fail: drm_encoder_cleanup(&wb_connector->encoder); fail: drm_property_blob_put(blob); return ret; } EXPORT_SYMBOL(drm_writeback_connector_init); /** * drm_writeback_queue_job - Queue a writeback job for later signalling * @wb_connector: The writeback connector to queue a job on * @job: The job to queue * * This function adds a job to the job_queue for a writeback connector. It * should be considered to take ownership of the writeback job, and so any other * references to the job must be cleared after calling this function. * * Drivers must ensure that for a given writeback connector, jobs are queued in * exactly the same order as they will be completed by the hardware (and * signaled via drm_writeback_signal_completion). * * For every call to drm_writeback_queue_job() there must be exactly one call to * drm_writeback_signal_completion() * * See also: drm_writeback_signal_completion() */ void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector, struct drm_writeback_job *job) { unsigned long flags; spin_lock_irqsave(&wb_connector->job_lock, flags); list_add_tail(&job->list_entry, &wb_connector->job_queue); spin_unlock_irqrestore(&wb_connector->job_lock, flags); } EXPORT_SYMBOL(drm_writeback_queue_job); /* * @cleanup_work: deferred cleanup of a writeback job * * The job cannot be cleaned up directly in drm_writeback_signal_completion, * because it may be called in interrupt context. Dropping the framebuffer * reference can sleep, and so the cleanup is deferred to a workqueue. */ static void cleanup_work(struct work_struct *work) { struct drm_writeback_job *job = container_of(work, struct drm_writeback_job, cleanup_work); drm_framebuffer_put(job->fb); kfree(job); } /** * drm_writeback_signal_completion - Signal the completion of a writeback job * @wb_connector: The writeback connector whose job is complete * * Drivers should call this to signal the completion of a previously queued * writeback job. It should be called as soon as possible after the hardware * has finished writing, and may be called from interrupt context. * It is the driver's responsibility to ensure that for a given connector, the * hardware completes writeback jobs in the same order as they are queued. * * Unless the driver is holding its own reference to the framebuffer, it must * not be accessed after calling this function. * * See also: drm_writeback_queue_job() */ void drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector) { unsigned long flags; struct drm_writeback_job *job; spin_lock_irqsave(&wb_connector->job_lock, flags); job = list_first_entry_or_null(&wb_connector->job_queue, struct drm_writeback_job, list_entry); if (job) list_del(&job->list_entry); spin_unlock_irqrestore(&wb_connector->job_lock, flags); if (WARN_ON(!job)) return; INIT_WORK(&job->cleanup_work, cleanup_work); queue_work(system_long_wq, &job->cleanup_work); } EXPORT_SYMBOL(drm_writeback_signal_completion);