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Diffstat (limited to 'drivers/gpu/drm/drm_writeback.c')
| -rw-r--r-- | drivers/gpu/drm/drm_writeback.c | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c new file mode 100644 index 000000000000..c20e6fe00cb3 --- /dev/null +++ b/drivers/gpu/drm/drm_writeback.c @@ -0,0 +1,353 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * (C) COPYRIGHT 2016 ARM Limited. All rights reserved. + * Author: Brian Starkey <brian.starkey@arm.com> + * + * 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 <drm/drm_crtc.h> +#include <drm/drm_modeset_helper_vtables.h> +#include <drm/drm_property.h> +#include <drm/drm_writeback.h> +#include <drm/drmP.h> +#include <linux/dma-fence.h> + +/** + * 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 are visible to userspace only when the client sets + * DRM_CLIENT_CAP_WRITEBACK_CONNECTORS. + * + * * 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. + * + * Unlike with planes, when a writeback framebuffer is removed by userspace DRM + * makes no attempt to remove it from active use by the connector. This is + * because no method is provided to abort a writeback operation, and in any + * case making a new commit whilst a writeback is ongoing is undefined (see + * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished, + * the framebuffer will automatically no longer be in active use. As it will + * also have already been removed from the framebuffer list, there will be no + * way for any userspace application to retrieve a reference to it in the + * intervening period. + * + * 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. + * + * "WRITEBACK_OUT_FENCE_PTR": + * Userspace can use this property to provide a pointer for the kernel to + * fill with a sync_file file descriptor, which will signal once the + * writeback is finished. The value should be the address of a 32-bit + * signed integer, cast to a u64. + * Userspace should wait for this fence to signal before making another + * commit affecting any of the same CRTCs, Planes or Connectors. + * **Failure to do so will result in undefined behaviour.** + * For this reason it is strongly recommended that all userspace + * applications making use of writeback connectors *always* retrieve an + * out-fence for the commit and use it appropriately. + * From userspace, this property will always read as zero. + */ + +#define fence_to_wb_connector(x) container_of(x->lock, \ + struct drm_writeback_connector, \ + fence_lock) + +static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence) +{ + struct drm_writeback_connector *wb_connector = + fence_to_wb_connector(fence); + + return wb_connector->base.dev->driver->name; +} + +static const char * +drm_writeback_fence_get_timeline_name(struct dma_fence *fence) +{ + struct drm_writeback_connector *wb_connector = + fence_to_wb_connector(fence); + + return wb_connector->timeline_name; +} + +static bool drm_writeback_fence_enable_signaling(struct dma_fence *fence) +{ + return true; +} + +static const struct dma_fence_ops drm_writeback_fence_ops = { + .get_driver_name = drm_writeback_fence_get_driver_name, + .get_timeline_name = drm_writeback_fence_get_timeline_name, + .enable_signaling = drm_writeback_fence_enable_signaling, + .wait = dma_fence_default_wait, +}; + +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; + } + + if (!dev->mode_config.writeback_out_fence_ptr_property) { + prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC, + "WRITEBACK_OUT_FENCE_PTR", 0, + U64_MAX); + if (!prop) + return -ENOMEM; + dev->mode_config.writeback_out_fence_ptr_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_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); + + wb_connector->fence_context = dma_fence_context_alloc(1); + spin_lock_init(&wb_connector->fence_lock); + snprintf(wb_connector->timeline_name, + sizeof(wb_connector->timeline_name), + "CONNECTOR:%d-%s", connector->base.id, connector->name); + + drm_object_attach_property(&connector->base, + config->writeback_out_fence_ptr_property, 0); + + 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 + * @status: Status code to set in the writeback out_fence (0 for success) + * + * 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, + int status) +{ + 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); + if (job->out_fence) { + if (status) + dma_fence_set_error(job->out_fence, status); + dma_fence_signal(job->out_fence); + dma_fence_put(job->out_fence); + } + } + 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); + +struct dma_fence * +drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector) +{ + struct dma_fence *fence; + + if (WARN_ON(wb_connector->base.connector_type != + DRM_MODE_CONNECTOR_WRITEBACK)) + return NULL; + + fence = kzalloc(sizeof(*fence), GFP_KERNEL); + if (!fence) + return NULL; + + dma_fence_init(fence, &drm_writeback_fence_ops, + &wb_connector->fence_lock, wb_connector->fence_context, + ++wb_connector->fence_seqno); + + return fence; +} +EXPORT_SYMBOL(drm_writeback_get_out_fence); |