drivers/gpu/drm/amd/scheduler/gpu_scheduler.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright 2015 Advanced Micro Devices, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  *
  */
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
 #include <drm/drmP.h>
 #include "gpu_scheduler.h"

 static struct amd_sched_job *
 amd_sched_entity_pop_job(struct amd_sched_entity *entity);
 static void amd_sched_wakeup(struct amd_gpu_scheduler *sched);

 /* Initialize a given run queue struct */
 static void amd_sched_rq_init(struct amd_sched_rq *rq)
 {
 	spin_lock_init(&rq->lock);
 	INIT_LIST_HEAD(&rq->entities);
 	rq->current_entity = NULL;
 }

 static void amd_sched_rq_add_entity(struct amd_sched_rq *rq,
 				    struct amd_sched_entity *entity)
 {
 	spin_lock(&rq->lock);
 	list_add_tail(&entity->list, &rq->entities);
 	spin_unlock(&rq->lock);
 }

 static void amd_sched_rq_remove_entity(struct amd_sched_rq *rq,
 				       struct amd_sched_entity *entity)
 {
 	spin_lock(&rq->lock);
 	list_del_init(&entity->list);
 	if (rq->current_entity == entity)
 		rq->current_entity = NULL;
 	spin_unlock(&rq->lock);
 }

 /**
  * Select next job from a specified run queue with round robin policy.
  * Return NULL if nothing available.
  */
 static struct amd_sched_job *
 amd_sched_rq_select_job(struct amd_sched_rq *rq)
 {
 	struct amd_sched_entity *entity;
 	struct amd_sched_job *job;

 	spin_lock(&rq->lock);

 	entity = rq->current_entity;
 	if (entity) {
 		list_for_each_entry_continue(entity, &rq->entities, list) {
 			job = amd_sched_entity_pop_job(entity);
 			if (job) {
 				rq->current_entity = entity;
 				spin_unlock(&rq->lock);
 				return job;
 			}
 		}
 	}

 	list_for_each_entry(entity, &rq->entities, list) {

 		job = amd_sched_entity_pop_job(entity);
 		if (job) {
 			rq->current_entity = entity;
 			spin_unlock(&rq->lock);
 			return job;
 		}

 		if (entity == rq->current_entity)
 			break;
 	}

 	spin_unlock(&rq->lock);

 	return NULL;
 }

 /**
  * Init a context entity used by scheduler when submit to HW ring.
  *
  * @sched	The pointer to the scheduler
  * @entity	The pointer to a valid amd_sched_entity
  * @rq		The run queue this entity belongs
  * @kernel	If this is an entity for the kernel
  * @jobs	The max number of jobs in the job queue
  *
  * return 0 if succeed. negative error code on failure
 */
 int amd_sched_entity_init(struct amd_gpu_scheduler *sched,
 			  struct amd_sched_entity *entity,
 			  struct amd_sched_rq *rq,
 			  uint32_t jobs)
 {
 	if (!(sched && entity && rq))
 		return -EINVAL;

 	memset(entity, 0, sizeof(struct amd_sched_entity));
 	entity->belongto_rq = rq;
 	entity->scheduler = sched;
 	entity->fence_context = fence_context_alloc(1);
 	if(kfifo_alloc(&entity->job_queue,
 		       jobs * sizeof(void *),
 		       GFP_KERNEL))
 		return -EINVAL;

 	spin_lock_init(&entity->queue_lock);
 	atomic_set(&entity->fence_seq, 0);

 	/* Add the entity to the run queue */
 	amd_sched_rq_add_entity(rq, entity);
 	return 0;
 }

 /**
  * Query if entity is initialized
  *
  * @sched       Pointer to scheduler instance
  * @entity	The pointer to a valid scheduler entity
  *
  * return true if entity is initialized, false otherwise
 */
 static bool amd_sched_entity_is_initialized(struct amd_gpu_scheduler *sched,
 					    struct amd_sched_entity *entity)
 {
 	return entity->scheduler == sched &&
 		entity->belongto_rq != NULL;
 }

 /**
  * Check if entity is idle
  *
  * @entity	The pointer to a valid scheduler entity
  *
  * Return true if entity don't has any unscheduled jobs.
  */
 static bool amd_sched_entity_is_idle(struct amd_sched_entity *entity)
 {
 	rmb();
 	if (kfifo_is_empty(&entity->job_queue))
 		return true;

 	return false;
 }

 /**
  * Destroy a context entity
  *
  * @sched       Pointer to scheduler instance
  * @entity	The pointer to a valid scheduler entity
  *
  * Cleanup and free the allocated resources.
  */
 void amd_sched_entity_fini(struct amd_gpu_scheduler *sched,
 			   struct amd_sched_entity *entity)
 {
 	struct amd_sched_rq *rq = entity->belongto_rq;

 	if (!amd_sched_entity_is_initialized(sched, entity))
 		return;

 	/**
 	 * The client will not queue more IBs during this fini, consume existing
 	 * queued IBs
 	*/
 	wait_event(sched->job_scheduled, amd_sched_entity_is_idle(entity));

 	amd_sched_rq_remove_entity(rq, entity);
 	kfifo_free(&entity->job_queue);
 }

 static void amd_sched_entity_wakeup(struct fence *f, struct fence_cb *cb)
 {
 	struct amd_sched_entity *entity =
 		container_of(cb, struct amd_sched_entity, cb);
 	entity->dependency = NULL;
 	fence_put(f);
 	amd_sched_wakeup(entity->scheduler);
 }

 static struct amd_sched_job *
 amd_sched_entity_pop_job(struct amd_sched_entity *entity)
 {
 	struct amd_gpu_scheduler *sched = entity->scheduler;
 	struct amd_sched_job *job;

 	if (ACCESS_ONCE(entity->dependency))
 		return NULL;

 	if (!kfifo_out_peek(&entity->job_queue, &job, sizeof(job)))
 		return NULL;

 	while ((entity->dependency = sched->ops->dependency(job))) {

 		if (fence_add_callback(entity->dependency, &entity->cb,
 				       amd_sched_entity_wakeup))
 			fence_put(entity->dependency);
 		else
 			return NULL;
 	}

 	return job;
 }

 /**
  * Helper to submit a job to the job queue
  *
  * @job		The pointer to job required to submit
  *
  * Returns true if we could submit the job.
  */
 static bool amd_sched_entity_in(struct amd_sched_job *job)
 {
 	struct amd_sched_entity *entity = job->s_entity;
 	bool added, first = false;

 	spin_lock(&entity->queue_lock);
 	added = kfifo_in(&entity->job_queue, &job, sizeof(job)) == sizeof(job);

 	if (added && kfifo_len(&entity->job_queue) == sizeof(job))
 		first = true;

 	spin_unlock(&entity->queue_lock);

 	/* first job wakes up scheduler */
 	if (first)
 		amd_sched_wakeup(job->sched);

 	return added;
 }

 /**
  * Submit a job to the job queue
  *
  * @job		The pointer to job required to submit
  *
  * Returns 0 for success, negative error code otherwise.
  */
 int amd_sched_entity_push_job(struct amd_sched_job *sched_job)
 {
 	struct amd_sched_entity *entity = sched_job->s_entity;
 	struct amd_sched_fence *fence = amd_sched_fence_create(
 		entity, sched_job->owner);

 	if (!fence)
 		return -ENOMEM;

 	fence_get(&fence->base);
 	sched_job->s_fence = fence;

 	wait_event(entity->scheduler->job_scheduled,
 		   amd_sched_entity_in(sched_job));

 	return 0;
 }

 /**
  * Return ture if we can push more jobs to the hw.
  */
 static bool amd_sched_ready(struct amd_gpu_scheduler *sched)
 {
 	return atomic_read(&sched->hw_rq_count) <
 		sched->hw_submission_limit;
 }

 /**
  * Wake up the scheduler when it is ready
  */
 static void amd_sched_wakeup(struct amd_gpu_scheduler *sched)
 {
 	if (amd_sched_ready(sched))
 		wake_up_interruptible(&sched->wake_up_worker);
 }

 /**
  * Select next to run
 */
 static struct amd_sched_job *
 amd_sched_select_job(struct amd_gpu_scheduler *sched)
 {
 	struct amd_sched_job *job;

 	if (!amd_sched_ready(sched))
 		return NULL;

 	/* Kernel run queue has higher priority than normal run queue*/
 	job = amd_sched_rq_select_job(&sched->kernel_rq);
 	if (job == NULL)
 		job = amd_sched_rq_select_job(&sched->sched_rq);

 	return job;
 }

 static void amd_sched_process_job(struct fence *f, struct fence_cb *cb)
 {
 	struct amd_sched_job *sched_job =
 		container_of(cb, struct amd_sched_job, cb);
 	struct amd_gpu_scheduler *sched;

 	sched = sched_job->sched;
 	amd_sched_fence_signal(sched_job->s_fence);
 	atomic_dec(&sched->hw_rq_count);
 	fence_put(&sched_job->s_fence->base);
 	sched->ops->process_job(sched_job);
 	wake_up_interruptible(&sched->wake_up_worker);
 }

 static int amd_sched_main(void *param)
 {
 	struct sched_param sparam = {.sched_priority = 1};
 	struct amd_gpu_scheduler *sched = (struct amd_gpu_scheduler *)param;
 	int r, count;

 	sched_setscheduler(current, SCHED_FIFO, &sparam);

 	while (!kthread_should_stop()) {
 		struct amd_sched_entity *entity;
 		struct amd_sched_job *job;
 		struct fence *fence;

 		wait_event_interruptible(sched->wake_up_worker,
 			kthread_should_stop() ||
 			(job = amd_sched_select_job(sched)));

 		if (!job)
 			continue;

 		entity = job->s_entity;
 		atomic_inc(&sched->hw_rq_count);
 		fence = sched->ops->run_job(job);
 		if (fence) {
 			r = fence_add_callback(fence, &job->cb,
 					       amd_sched_process_job);
 			if (r == -ENOENT)
 				amd_sched_process_job(fence, &job->cb);
 			else if (r)
 				DRM_ERROR("fence add callback failed (%d)\n", r);
 			fence_put(fence);
 		}

 		count = kfifo_out(&entity->job_queue, &job, sizeof(job));
 		WARN_ON(count != sizeof(job));
 		wake_up(&sched->job_scheduled);
 	}
 	return 0;
 }

 /**
  * Create a gpu scheduler
  *
  * @ops			The backend operations for this scheduler.
  * @ring		The the ring id for the scheduler.
  * @hw_submissions	Number of hw submissions to do.
  *
  * Return the pointer to scheduler for success, otherwise return NULL
 */
 struct amd_gpu_scheduler *amd_sched_create(struct amd_sched_backend_ops *ops,
 					   unsigned ring, unsigned hw_submission,
 					   void *priv)
 {
 	struct amd_gpu_scheduler *sched;

 	sched = kzalloc(sizeof(struct amd_gpu_scheduler), GFP_KERNEL);
 	if (!sched)
 		return NULL;

 	sched->ops = ops;
 	sched->ring_id = ring;
 	sched->hw_submission_limit = hw_submission;
 	sched->priv = priv;
 	snprintf(sched->name, sizeof(sched->name), "amdgpu[%d]", ring);
 	amd_sched_rq_init(&sched->sched_rq);
 	amd_sched_rq_init(&sched->kernel_rq);

 	init_waitqueue_head(&sched->wake_up_worker);
 	init_waitqueue_head(&sched->job_scheduled);
 	atomic_set(&sched->hw_rq_count, 0);
 	/* Each scheduler will run on a seperate kernel thread */
 	sched->thread = kthread_run(amd_sched_main, sched, sched->name);
 	if (IS_ERR(sched->thread)) {
 		DRM_ERROR("Failed to create scheduler for id %d.\n", ring);
 		kfree(sched);
 		return NULL;
 	}

 	return sched;
 }

 /**
  * Destroy a gpu scheduler
  *
  * @sched	The pointer to the scheduler
  *
  * return 0 if succeed. -1 if failed.
  */
 int amd_sched_destroy(struct amd_gpu_scheduler *sched)
 {
 	kthread_stop(sched->thread);
 	kfree(sched);
 	return  0;
 }
	/*
	* Copyright 2015 Advanced Micro Devices, Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*
	*
	*/
	#include <linux/kthread.h>
	#include <linux/wait.h>
	#include <linux/sched.h>
	#include <drm/drmP.h>
	#include "gpu_scheduler.h"

	static struct amd_sched_job *
	amd_sched_entity_pop_job(struct amd_sched_entity *entity);
	static void amd_sched_wakeup(struct amd_gpu_scheduler *sched);

	/* Initialize a given run queue struct */
	static void amd_sched_rq_init(struct amd_sched_rq *rq)
	{
	spin_lock_init(&rq->lock);
	INIT_LIST_HEAD(&rq->entities);
	rq->current_entity = NULL;
	}

	static void amd_sched_rq_add_entity(struct amd_sched_rq *rq,
	struct amd_sched_entity *entity)
	{
	spin_lock(&rq->lock);
	list_add_tail(&entity->list, &rq->entities);
	spin_unlock(&rq->lock);
	}

	static void amd_sched_rq_remove_entity(struct amd_sched_rq *rq,
	struct amd_sched_entity *entity)
	{
	spin_lock(&rq->lock);
	list_del_init(&entity->list);
	if (rq->current_entity == entity)
	rq->current_entity = NULL;
	spin_unlock(&rq->lock);
	}

	/**
	* Select next job from a specified run queue with round robin policy.
	* Return NULL if nothing available.
	*/
	static struct amd_sched_job *
	amd_sched_rq_select_job(struct amd_sched_rq *rq)
	{
	struct amd_sched_entity *entity;
	struct amd_sched_job *job;

	spin_lock(&rq->lock);

	entity = rq->current_entity;
	if (entity) {
	list_for_each_entry_continue(entity, &rq->entities, list) {
	job = amd_sched_entity_pop_job(entity);
	if (job) {
	rq->current_entity = entity;
	spin_unlock(&rq->lock);
	return job;
	}
	}
	}

	list_for_each_entry(entity, &rq->entities, list) {

	job = amd_sched_entity_pop_job(entity);
	if (job) {
	rq->current_entity = entity;
	spin_unlock(&rq->lock);
	return job;
	}

	if (entity == rq->current_entity)
	break;
	}

	spin_unlock(&rq->lock);

	return NULL;
	}

	/**
	* Init a context entity used by scheduler when submit to HW ring.
	*
	* @sched The pointer to the scheduler
	* @entity The pointer to a valid amd_sched_entity
	* @rq The run queue this entity belongs
	* @kernel If this is an entity for the kernel
	* @jobs The max number of jobs in the job queue
	*
	* return 0 if succeed. negative error code on failure
	*/
	int amd_sched_entity_init(struct amd_gpu_scheduler *sched,
	struct amd_sched_entity *entity,
	struct amd_sched_rq *rq,
	uint32_t jobs)
	{
	if (!(sched && entity && rq))
	return -EINVAL;

	memset(entity, 0, sizeof(struct amd_sched_entity));
	entity->belongto_rq = rq;
	entity->scheduler = sched;
	entity->fence_context = fence_context_alloc(1);
	if(kfifo_alloc(&entity->job_queue,
	jobs * sizeof(void *),
	GFP_KERNEL))
	return -EINVAL;

	spin_lock_init(&entity->queue_lock);
	atomic_set(&entity->fence_seq, 0);

	/* Add the entity to the run queue */
	amd_sched_rq_add_entity(rq, entity);
	return 0;
	}

	/**
	* Query if entity is initialized
	*
	* @sched Pointer to scheduler instance
	* @entity The pointer to a valid scheduler entity
	*
	* return true if entity is initialized, false otherwise
	*/
	static bool amd_sched_entity_is_initialized(struct amd_gpu_scheduler *sched,
	struct amd_sched_entity *entity)
	{
	return entity->scheduler == sched &&
	entity->belongto_rq != NULL;
	}

	/**
	* Check if entity is idle
	*
	* @entity The pointer to a valid scheduler entity
	*
	* Return true if entity don't has any unscheduled jobs.
	*/
	static bool amd_sched_entity_is_idle(struct amd_sched_entity *entity)
	{
	rmb();
	if (kfifo_is_empty(&entity->job_queue))
	return true;

	return false;
	}

	/**
	* Destroy a context entity
	*
	* @sched Pointer to scheduler instance
	* @entity The pointer to a valid scheduler entity
	*
	* Cleanup and free the allocated resources.
	*/
	void amd_sched_entity_fini(struct amd_gpu_scheduler *sched,
	struct amd_sched_entity *entity)
	{
	struct amd_sched_rq *rq = entity->belongto_rq;

	if (!amd_sched_entity_is_initialized(sched, entity))
	return;

	/**
	* The client will not queue more IBs during this fini, consume existing
	* queued IBs
	*/
	wait_event(sched->job_scheduled, amd_sched_entity_is_idle(entity));

	amd_sched_rq_remove_entity(rq, entity);
	kfifo_free(&entity->job_queue);
	}

	static void amd_sched_entity_wakeup(struct fence f, struct fence_cb cb)
	{
	struct amd_sched_entity *entity =
	container_of(cb, struct amd_sched_entity, cb);
	entity->dependency = NULL;
	fence_put(f);
	amd_sched_wakeup(entity->scheduler);
	}

	static struct amd_sched_job *
	amd_sched_entity_pop_job(struct amd_sched_entity *entity)
	{
	struct amd_gpu_scheduler *sched = entity->scheduler;
	struct amd_sched_job *job;

	if (ACCESS_ONCE(entity->dependency))
	return NULL;

	if (!kfifo_out_peek(&entity->job_queue, &job, sizeof(job)))
	return NULL;

	while ((entity->dependency = sched->ops->dependency(job))) {

	if (fence_add_callback(entity->dependency, &entity->cb,
	amd_sched_entity_wakeup))
	fence_put(entity->dependency);
	else
	return NULL;
	}

	return job;
	}

	/**
	* Helper to submit a job to the job queue
	*
	* @job The pointer to job required to submit
	*
	* Returns true if we could submit the job.
	*/
	static bool amd_sched_entity_in(struct amd_sched_job *job)
	{
	struct amd_sched_entity *entity = job->s_entity;
	bool added, first = false;

	spin_lock(&entity->queue_lock);
	added = kfifo_in(&entity->job_queue, &job, sizeof(job)) == sizeof(job);

	if (added && kfifo_len(&entity->job_queue) == sizeof(job))
	first = true;

	spin_unlock(&entity->queue_lock);

	/* first job wakes up scheduler */
	if (first)
	amd_sched_wakeup(job->sched);

	return added;
	}

	/**
	* Submit a job to the job queue
	*
	* @job The pointer to job required to submit
	*
	* Returns 0 for success, negative error code otherwise.
	*/
	int amd_sched_entity_push_job(struct amd_sched_job *sched_job)
	{
	struct amd_sched_entity *entity = sched_job->s_entity;
	struct amd_sched_fence *fence = amd_sched_fence_create(
	entity, sched_job->owner);

	if (!fence)
	return -ENOMEM;

	fence_get(&fence->base);
	sched_job->s_fence = fence;

	wait_event(entity->scheduler->job_scheduled,
	amd_sched_entity_in(sched_job));

	return 0;
	}

	/**
	* Return ture if we can push more jobs to the hw.
	*/
	static bool amd_sched_ready(struct amd_gpu_scheduler *sched)
	{
	return atomic_read(&sched->hw_rq_count) <
	sched->hw_submission_limit;
	}

	/**
	* Wake up the scheduler when it is ready
	*/
	static void amd_sched_wakeup(struct amd_gpu_scheduler *sched)
	{
	if (amd_sched_ready(sched))
	wake_up_interruptible(&sched->wake_up_worker);
	}

	/**
	* Select next to run
	*/
	static struct amd_sched_job *
	amd_sched_select_job(struct amd_gpu_scheduler *sched)
	{
	struct amd_sched_job *job;

	if (!amd_sched_ready(sched))
	return NULL;

	/* Kernel run queue has higher priority than normal run queue*/
	job = amd_sched_rq_select_job(&sched->kernel_rq);
	if (job == NULL)
	job = amd_sched_rq_select_job(&sched->sched_rq);

	return job;
	}

	static void amd_sched_process_job(struct fence f, struct fence_cb cb)
	{
	struct amd_sched_job *sched_job =
	container_of(cb, struct amd_sched_job, cb);
	struct amd_gpu_scheduler *sched;

	sched = sched_job->sched;
	amd_sched_fence_signal(sched_job->s_fence);
	atomic_dec(&sched->hw_rq_count);
	fence_put(&sched_job->s_fence->base);
	sched->ops->process_job(sched_job);
	wake_up_interruptible(&sched->wake_up_worker);
	}

	static int amd_sched_main(void *param)
	{
	struct sched_param sparam = {.sched_priority = 1};
	struct amd_gpu_scheduler sched = (struct amd_gpu_scheduler )param;
	int r, count;

	sched_setscheduler(current, SCHED_FIFO, &sparam);

	while (!kthread_should_stop()) {
	struct amd_sched_entity *entity;
	struct amd_sched_job *job;
	struct fence *fence;

	wait_event_interruptible(sched->wake_up_worker,
	kthread_should_stop() \|\|
	(job = amd_sched_select_job(sched)));

	if (!job)
	continue;

	entity = job->s_entity;
	atomic_inc(&sched->hw_rq_count);
	fence = sched->ops->run_job(job);
	if (fence) {
	r = fence_add_callback(fence, &job->cb,
	amd_sched_process_job);
	if (r == -ENOENT)
	amd_sched_process_job(fence, &job->cb);
	else if (r)
	DRM_ERROR("fence add callback failed (%d)\n", r);
	fence_put(fence);
	}

	count = kfifo_out(&entity->job_queue, &job, sizeof(job));
	WARN_ON(count != sizeof(job));
	wake_up(&sched->job_scheduled);
	}
	return 0;
	}

	/**
	* Create a gpu scheduler
	*
	* @ops The backend operations for this scheduler.
	* @ring The the ring id for the scheduler.
	* @hw_submissions Number of hw submissions to do.
	*
	* Return the pointer to scheduler for success, otherwise return NULL
	*/
	struct amd_gpu_scheduler amd_sched_create(struct amd_sched_backend_ops ops,
	unsigned ring, unsigned hw_submission,
	void *priv)
	{
	struct amd_gpu_scheduler *sched;

	sched = kzalloc(sizeof(struct amd_gpu_scheduler), GFP_KERNEL);
	if (!sched)
	return NULL;

	sched->ops = ops;
	sched->ring_id = ring;
	sched->hw_submission_limit = hw_submission;
	sched->priv = priv;
	snprintf(sched->name, sizeof(sched->name), "amdgpu[%d]", ring);
	amd_sched_rq_init(&sched->sched_rq);
	amd_sched_rq_init(&sched->kernel_rq);

	init_waitqueue_head(&sched->wake_up_worker);
	init_waitqueue_head(&sched->job_scheduled);
	atomic_set(&sched->hw_rq_count, 0);
	/* Each scheduler will run on a seperate kernel thread */
	sched->thread = kthread_run(amd_sched_main, sched, sched->name);
	if (IS_ERR(sched->thread)) {
	DRM_ERROR("Failed to create scheduler for id %d.\n", ring);
	kfree(sched);
	return NULL;
	}

	return sched;
	}

	/**
	* Destroy a gpu scheduler
	*
	* @sched The pointer to the scheduler
	*
	* return 0 if succeed. -1 if failed.
	*/
	int amd_sched_destroy(struct amd_gpu_scheduler *sched)
	{
	kthread_stop(sched->thread);
	kfree(sched);
	return 0;
	}