drivers/gpu/drm/drm_writeback.c - linux-mtk - Git at Google

 // 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);
	// 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);