Adding upstream version 6.8.9.upstream/6.8.9

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 352 insertions, 153 deletions

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
index 3143ecaaf..f8ed093b7 100644
--- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
@@ -51,7 +51,7 @@ DECLARE_EVENT_CLASS(drm_sched_job,
 			   __assign_str(name, sched_job->sched->name);
 			   __entry->job_count = spsc_queue_count(&entity->job_queue);
 			   __entry->hw_job_count = atomic_read(
-				   &sched_job->sched->hw_rq_count);
+				   &sched_job->sched->credit_count);
 			   ),
 	    TP_printk("entity=%p, id=%llu, fence=%p, ring=%s, job count:%u, hw job count:%d",
 		      __entry->entity, __entry->id,
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 9ee928982..58c816128 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -88,13 +88,14 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
 		pr_warn("%s: called with uninitialized scheduler\n", __func__);
 	} else if (num_sched_list) {
 		/* The "priority" of an entity cannot exceed the number of run-queues of a
-		 * scheduler. Protect against num_rqs being 0, by converting to signed.
+		 * scheduler. Protect against num_rqs being 0, by converting to signed. Choose
+		 * the lowest priority available.
 		 */
 		if (entity->priority >= sched_list[0]->num_rqs) {
 			drm_err(sched_list[0], "entity with out-of-bounds priority:%u num_rqs:%u\n",
 				entity->priority, sched_list[0]->num_rqs);
 			entity->priority = max_t(s32, (s32) sched_list[0]->num_rqs - 1,
-						 (s32) DRM_SCHED_PRIORITY_MIN);
+						 (s32) DRM_SCHED_PRIORITY_KERNEL);
 		}
 		entity->rq = sched_list[0]->sched_rq[entity->priority];
 	}
@@ -379,7 +380,7 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
 		container_of(cb, struct drm_sched_entity, cb);
 
 	drm_sched_entity_clear_dep(f, cb);
-	drm_sched_wakeup_if_can_queue(entity->rq->sched);
+	drm_sched_wakeup(entity->rq->sched, entity);
 }
 
 /**
@@ -611,7 +612,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
 		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
 			drm_sched_rq_update_fifo(entity, submit_ts);
 
-		drm_sched_wakeup_if_can_queue(entity->rq->sched);
+		drm_sched_wakeup(entity->rq->sched, entity);
 	}
 }
 EXPORT_SYMBOL(drm_sched_entity_push_job);
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 99797a8c8..d442b8932 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -48,7 +48,30 @@
  * through the jobs entity pointer.
  */
 
-#include <linux/kthread.h>
+/**
+ * DOC: Flow Control
+ *
+ * The DRM GPU scheduler provides a flow control mechanism to regulate the rate
+ * in which the jobs fetched from scheduler entities are executed.
+ *
+ * In this context the &drm_gpu_scheduler keeps track of a driver specified
+ * credit limit representing the capacity of this scheduler and a credit count;
+ * every &drm_sched_job carries a driver specified number of credits.
+ *
+ * Once a job is executed (but not yet finished), the job's credits contribute
+ * to the scheduler's credit count until the job is finished. If by executing
+ * one more job the scheduler's credit count would exceed the scheduler's
+ * credit limit, the job won't be executed. Instead, the scheduler will wait
+ * until the credit count has decreased enough to not overflow its credit limit.
+ * This implies waiting for previously executed jobs.
+ *
+ * Optionally, drivers may register a callback (update_job_credits) provided by
+ * struct drm_sched_backend_ops to update the job's credits dynamically. The
+ * scheduler executes this callback every time the scheduler considers a job for
+ * execution and subsequently checks whether the job fits the scheduler's credit
+ * limit.
+ */
+
 #include <linux/wait.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
@@ -76,6 +99,51 @@ int drm_sched_policy = DRM_SCHED_POLICY_FIFO;
 MODULE_PARM_DESC(sched_policy, "Specify the scheduling policy for entities on a run-queue, " __stringify(DRM_SCHED_POLICY_RR) " = Round Robin, " __stringify(DRM_SCHED_POLICY_FIFO) " = FIFO (default).");
 module_param_named(sched_policy, drm_sched_policy, int, 0444);
 
+static u32 drm_sched_available_credits(struct drm_gpu_scheduler *sched)
+{
+	u32 credits;
+
+	drm_WARN_ON(sched, check_sub_overflow(sched->credit_limit,
+					      atomic_read(&sched->credit_count),
+					      &credits));
+
+	return credits;
+}
+
+/**
+ * drm_sched_can_queue -- Can we queue more to the hardware?
+ * @sched: scheduler instance
+ * @entity: the scheduler entity
+ *
+ * Return true if we can push at least one more job from @entity, false
+ * otherwise.
+ */
+static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched,
+				struct drm_sched_entity *entity)
+{
+	struct drm_sched_job *s_job;
+
+	s_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
+	if (!s_job)
+		return false;
+
+	if (sched->ops->update_job_credits) {
+		s_job->credits = sched->ops->update_job_credits(s_job);
+
+		drm_WARN(sched, !s_job->credits,
+			 "Jobs with zero credits bypass job-flow control.\n");
+	}
+
+	/* If a job exceeds the credit limit, truncate it to the credit limit
+	 * itself to guarantee forward progress.
+	 */
+	if (drm_WARN(sched, s_job->credits > sched->credit_limit,
+		     "Jobs may not exceed the credit limit, truncate.\n"))
+		s_job->credits = sched->credit_limit;
+
+	return drm_sched_available_credits(sched) >= s_job->credits;
+}
+
 static __always_inline bool drm_sched_entity_compare_before(struct rb_node *a,
 							    const struct rb_node *b)
 {
@@ -187,12 +255,18 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
 /**
  * drm_sched_rq_select_entity_rr - Select an entity which could provide a job to run
  *
+ * @sched: the gpu scheduler
  * @rq: scheduler run queue to check.
  *
- * Try to find a ready entity, returns NULL if none found.
+ * Try to find the next ready entity.
+ *
+ * Return an entity if one is found; return an error-pointer (!NULL) if an
+ * entity was ready, but the scheduler had insufficient credits to accommodate
+ * its job; return NULL, if no ready entity was found.
  */
 static struct drm_sched_entity *
-drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq)
+drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched,
+			      struct drm_sched_rq *rq)
 {
 	struct drm_sched_entity *entity;
 
@@ -202,6 +276,14 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq)
 	if (entity) {
 		list_for_each_entry_continue(entity, &rq->entities, list) {
 			if (drm_sched_entity_is_ready(entity)) {
+				/* If we can't queue yet, preserve the current
+				 * entity in terms of fairness.
+				 */
+				if (!drm_sched_can_queue(sched, entity)) {
+					spin_unlock(&rq->lock);
+					return ERR_PTR(-ENOSPC);
+				}
+
 				rq->current_entity = entity;
 				reinit_completion(&entity->entity_idle);
 				spin_unlock(&rq->lock);
@@ -211,8 +293,15 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq)
 	}
 
 	list_for_each_entry(entity, &rq->entities, list) {
-
 		if (drm_sched_entity_is_ready(entity)) {
+			/* If we can't queue yet, preserve the current entity in
+			 * terms of fairness.
+			 */
+			if (!drm_sched_can_queue(sched, entity)) {
+				spin_unlock(&rq->lock);
+				return ERR_PTR(-ENOSPC);
+			}
+
 			rq->current_entity = entity;
 			reinit_completion(&entity->entity_idle);
 			spin_unlock(&rq->lock);
@@ -231,12 +320,18 @@ drm_sched_rq_select_entity_rr(struct drm_sched_rq *rq)
 /**
  * drm_sched_rq_select_entity_fifo - Select an entity which provides a job to run
  *
+ * @sched: the gpu scheduler
  * @rq: scheduler run queue to check.
  *
- * Find oldest waiting ready entity, returns NULL if none found.
+ * Find oldest waiting ready entity.
+ *
+ * Return an entity if one is found; return an error-pointer (!NULL) if an
+ * entity was ready, but the scheduler had insufficient credits to accommodate
+ * its job; return NULL, if no ready entity was found.
  */
 static struct drm_sched_entity *
-drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq)
+drm_sched_rq_select_entity_fifo(struct drm_gpu_scheduler *sched,
+				struct drm_sched_rq *rq)
 {
 	struct rb_node *rb;
 
@@ -246,6 +341,14 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq)
 
 		entity = rb_entry(rb, struct drm_sched_entity, rb_tree_node);
 		if (drm_sched_entity_is_ready(entity)) {
+			/* If we can't queue yet, preserve the current entity in
+			 * terms of fairness.
+			 */
+			if (!drm_sched_can_queue(sched, entity)) {
+				spin_unlock(&rq->lock);
+				return ERR_PTR(-ENOSPC);
+			}
+
 			rq->current_entity = entity;
 			reinit_completion(&entity->entity_idle);
 			break;
@@ -257,6 +360,42 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq)
 }
 
 /**
+ * drm_sched_run_job_queue - enqueue run-job work
+ * @sched: scheduler instance
+ */
+static void drm_sched_run_job_queue(struct drm_gpu_scheduler *sched)
+{
+	if (!READ_ONCE(sched->pause_submit))
+		queue_work(sched->submit_wq, &sched->work_run_job);
+}
+
+/**
+ * __drm_sched_run_free_queue - enqueue free-job work
+ * @sched: scheduler instance
+ */
+static void __drm_sched_run_free_queue(struct drm_gpu_scheduler *sched)
+{
+	if (!READ_ONCE(sched->pause_submit))
+		queue_work(sched->submit_wq, &sched->work_free_job);
+}
+
+/**
+ * drm_sched_run_free_queue - enqueue free-job work if ready
+ * @sched: scheduler instance
+ */
+static void drm_sched_run_free_queue(struct drm_gpu_scheduler *sched)
+{
+	struct drm_sched_job *job;
+
+	spin_lock(&sched->job_list_lock);
+	job = list_first_entry_or_null(&sched->pending_list,
+				       struct drm_sched_job, list);
+	if (job && dma_fence_is_signaled(&job->s_fence->finished))
+		__drm_sched_run_free_queue(sched);
+	spin_unlock(&sched->job_list_lock);
+}
+
+/**
  * drm_sched_job_done - complete a job
  * @s_job: pointer to the job which is done
  *
@@ -267,7 +406,7 @@ static void drm_sched_job_done(struct drm_sched_job *s_job, int result)
 	struct drm_sched_fence *s_fence = s_job->s_fence;
 	struct drm_gpu_scheduler *sched = s_fence->sched;
 
-	atomic_dec(&sched->hw_rq_count);
+	atomic_sub(s_job->credits, &sched->credit_count);
 	atomic_dec(sched->score);
 
 	trace_drm_sched_process_job(s_fence);
@@ -275,7 +414,7 @@ static void drm_sched_job_done(struct drm_sched_job *s_job, int result)
 	dma_fence_get(&s_fence->finished);
 	drm_sched_fence_finished(s_fence, result);
 	dma_fence_put(&s_fence->finished);
-	wake_up_interruptible(&sched->wake_up_worker);
+	__drm_sched_run_free_queue(sched);
 }
 
 /**
@@ -299,10 +438,35 @@ static void drm_sched_job_done_cb(struct dma_fence *f, struct dma_fence_cb *cb)
  */
 static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
 {
+	lockdep_assert_held(&sched->job_list_lock);
+
 	if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
 	    !list_empty(&sched->pending_list))
-		queue_delayed_work(sched->timeout_wq, &sched->work_tdr, sched->timeout);
+		mod_delayed_work(sched->timeout_wq, &sched->work_tdr, sched->timeout);
+}
+
+static void drm_sched_start_timeout_unlocked(struct drm_gpu_scheduler *sched)
+{
+	spin_lock(&sched->job_list_lock);
+	drm_sched_start_timeout(sched);
+	spin_unlock(&sched->job_list_lock);
+}
+
+/**
+ * drm_sched_tdr_queue_imm: - immediately start job timeout handler
+ *
+ * @sched: scheduler for which the timeout handling should be started.
+ *
+ * Start timeout handling immediately for the named scheduler.
+ */
+void drm_sched_tdr_queue_imm(struct drm_gpu_scheduler *sched)
+{
+	spin_lock(&sched->job_list_lock);
+	sched->timeout = 0;
+	drm_sched_start_timeout(sched);
+	spin_unlock(&sched->job_list_lock);
 }
+EXPORT_SYMBOL(drm_sched_tdr_queue_imm);
 
 /**
  * drm_sched_fault - immediately start timeout handler
@@ -388,7 +552,7 @@ static void drm_sched_job_timedout(struct work_struct *work)
 
 	sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
 
-	/* Protects against concurrent deletion in drm_sched_get_cleanup_job */
+	/* Protects against concurrent deletion in drm_sched_get_finished_job */
 	spin_lock(&sched->job_list_lock);
 	job = list_first_entry_or_null(&sched->pending_list,
 				       struct drm_sched_job, list);
@@ -416,11 +580,8 @@ static void drm_sched_job_timedout(struct work_struct *work)
 		spin_unlock(&sched->job_list_lock);
 	}
 
-	if (status != DRM_GPU_SCHED_STAT_ENODEV) {
-		spin_lock(&sched->job_list_lock);
-		drm_sched_start_timeout(sched);
-		spin_unlock(&sched->job_list_lock);
-	}
+	if (status != DRM_GPU_SCHED_STAT_ENODEV)
+		drm_sched_start_timeout_unlocked(sched);
 }
 
 /**
@@ -439,13 +600,13 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 {
 	struct drm_sched_job *s_job, *tmp;
 
-	kthread_park(sched->thread);
+	drm_sched_wqueue_stop(sched);
 
 	/*
 	 * Reinsert back the bad job here - now it's safe as
-	 * drm_sched_get_cleanup_job cannot race against us and release the
+	 * drm_sched_get_finished_job cannot race against us and release the
 	 * bad job at this point - we parked (waited for) any in progress
-	 * (earlier) cleanups and drm_sched_get_cleanup_job will not be called
+	 * (earlier) cleanups and drm_sched_get_finished_job will not be called
 	 * now until the scheduler thread is unparked.
 	 */
 	if (bad && bad->sched == sched)
@@ -468,7 +629,7 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 					      &s_job->cb)) {
 			dma_fence_put(s_job->s_fence->parent);
 			s_job->s_fence->parent = NULL;
-			atomic_dec(&sched->hw_rq_count);
+			atomic_sub(s_job->credits, &sched->credit_count);
 		} else {
 			/*
 			 * remove job from pending_list.
@@ -529,7 +690,7 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 	list_for_each_entry_safe(s_job, tmp, &sched->pending_list, list) {
 		struct dma_fence *fence = s_job->s_fence->parent;
 
-		atomic_inc(&sched->hw_rq_count);
+		atomic_add(s_job->credits, &sched->credit_count);
 
 		if (!full_recovery)
 			continue;
@@ -546,13 +707,10 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 			drm_sched_job_done(s_job, -ECANCELED);
 	}
 
-	if (full_recovery) {
-		spin_lock(&sched->job_list_lock);
-		drm_sched_start_timeout(sched);
-		spin_unlock(&sched->job_list_lock);
-	}
+	if (full_recovery)
+		drm_sched_start_timeout_unlocked(sched);
 
-	kthread_unpark(sched->thread);
+	drm_sched_wqueue_start(sched);
 }
 EXPORT_SYMBOL(drm_sched_start);
 
@@ -613,6 +771,8 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs);
  * drm_sched_job_init - init a scheduler job
  * @job: scheduler job to init
  * @entity: scheduler entity to use
+ * @credits: the number of credits this job contributes to the schedulers
+ * credit limit
  * @owner: job owner for debugging
  *
  * Refer to drm_sched_entity_push_job() documentation
@@ -630,7 +790,7 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs);
  */
 int drm_sched_job_init(struct drm_sched_job *job,
 		       struct drm_sched_entity *entity,
-		       void *owner)
+		       u32 credits, void *owner)
 {
 	if (!entity->rq) {
 		/* This will most likely be followed by missing frames
@@ -641,7 +801,13 @@ int drm_sched_job_init(struct drm_sched_job *job,
 		return -ENOENT;
 	}
 
+	if (unlikely(!credits)) {
+		pr_err("*ERROR* %s: credits cannot be 0!\n", __func__);
+		return -EINVAL;
+	}
+
 	job->entity = entity;
+	job->credits = credits;
 	job->s_fence = drm_sched_fence_alloc(entity, owner);
 	if (!job->s_fence)
 		return -ENOMEM;
@@ -854,27 +1020,17 @@ void drm_sched_job_cleanup(struct drm_sched_job *job)
 EXPORT_SYMBOL(drm_sched_job_cleanup);
 
 /**
- * drm_sched_can_queue -- Can we queue more to the hardware?
- * @sched: scheduler instance
- *
- * Return true if we can push more jobs to the hw, otherwise false.
- */
-static bool drm_sched_can_queue(struct drm_gpu_scheduler *sched)
-{
-	return atomic_read(&sched->hw_rq_count) <
-		sched->hw_submission_limit;
-}
-
-/**
- * drm_sched_wakeup_if_can_queue - Wake up the scheduler
+ * drm_sched_wakeup - Wake up the scheduler if it is ready to queue
  * @sched: scheduler instance
+ * @entity: the scheduler entity
  *
  * Wake up the scheduler if we can queue jobs.
  */
-void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched)
+void drm_sched_wakeup(struct drm_gpu_scheduler *sched,
+		      struct drm_sched_entity *entity)
 {
-	if (drm_sched_can_queue(sched))
-		wake_up_interruptible(&sched->wake_up_worker);
+	if (drm_sched_can_queue(sched, entity))
+		drm_sched_run_job_queue(sched);
 }
 
 /**
@@ -882,7 +1038,11 @@ void drm_sched_wakeup_if_can_queue(struct drm_gpu_scheduler *sched)
  *
  * @sched: scheduler instance
  *
- * Returns the entity to process or NULL if none are found.
+ * Return an entity to process or NULL if none are found.
+ *
+ * Note, that we break out of the for-loop when "entity" is non-null, which can
+ * also be an error-pointer--this assures we don't process lower priority
+ * run-queues. See comments in the respectively called functions.
  */
 static struct drm_sched_entity *
 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
@@ -890,23 +1050,21 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 	struct drm_sched_entity *entity;
 	int i;
 
-	if (!drm_sched_can_queue(sched))
-		return NULL;
-
-	/* Kernel run queue has higher priority than normal run queue*/
-	for (i = sched->num_rqs - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
+	/* Start with the highest priority.
+	 */
+	for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) {
 		entity = drm_sched_policy == DRM_SCHED_POLICY_FIFO ?
-			drm_sched_rq_select_entity_fifo(sched->sched_rq[i]) :
-			drm_sched_rq_select_entity_rr(sched->sched_rq[i]);
+			drm_sched_rq_select_entity_fifo(sched, sched->sched_rq[i]) :
+			drm_sched_rq_select_entity_rr(sched, sched->sched_rq[i]);
 		if (entity)
 			break;
 	}
 
-	return entity;
+	return IS_ERR(entity) ? NULL : entity;
 }
 
 /**
- * drm_sched_get_cleanup_job - fetch the next finished job to be destroyed
+ * drm_sched_get_finished_job - fetch the next finished job to be destroyed
  *
  * @sched: scheduler instance
  *
@@ -914,7 +1072,7 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
  * ready for it to be destroyed.
  */
 static struct drm_sched_job *
-drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
+drm_sched_get_finished_job(struct drm_gpu_scheduler *sched)
 {
 	struct drm_sched_job *job, *next;
 
@@ -934,8 +1092,10 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
 						typeof(*next), list);
 
 		if (next) {
-			next->s_fence->scheduled.timestamp =
-				dma_fence_timestamp(&job->s_fence->finished);
+			if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT,
+				     &next->s_fence->scheduled.flags))
+				next->s_fence->scheduled.timestamp =
+					dma_fence_timestamp(&job->s_fence->finished);
 			/* start TO timer for next job */
 			drm_sched_start_timeout(sched);
 		}
@@ -985,91 +1145,84 @@ drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
 EXPORT_SYMBOL(drm_sched_pick_best);
 
 /**
- * drm_sched_blocked - check if the scheduler is blocked
- *
- * @sched: scheduler instance
+ * drm_sched_free_job_work - worker to call free_job
  *
- * Returns true if blocked, otherwise false.
+ * @w: free job work
  */
-static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
+static void drm_sched_free_job_work(struct work_struct *w)
 {
-	if (kthread_should_park()) {
-		kthread_parkme();
-		return true;
-	}
+	struct drm_gpu_scheduler *sched =
+		container_of(w, struct drm_gpu_scheduler, work_free_job);
+	struct drm_sched_job *job;
+
+	if (READ_ONCE(sched->pause_submit))
+		return;
 
-	return false;
+	job = drm_sched_get_finished_job(sched);
+	if (job)
+		sched->ops->free_job(job);
+
+	drm_sched_run_free_queue(sched);
+	drm_sched_run_job_queue(sched);
 }
 
 /**
- * drm_sched_main - main scheduler thread
- *
- * @param: scheduler instance
+ * drm_sched_run_job_work - worker to call run_job
  *
- * Returns 0.
+ * @w: run job work
  */
-static int drm_sched_main(void *param)
+static void drm_sched_run_job_work(struct work_struct *w)
 {
-	struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
+	struct drm_gpu_scheduler *sched =
+		container_of(w, struct drm_gpu_scheduler, work_run_job);
+	struct drm_sched_entity *entity;
+	struct dma_fence *fence;
+	struct drm_sched_fence *s_fence;
+	struct drm_sched_job *sched_job;
 	int r;
 
-	sched_set_fifo_low(current);
-
-	while (!kthread_should_stop()) {
-		struct drm_sched_entity *entity = NULL;
-		struct drm_sched_fence *s_fence;
-		struct drm_sched_job *sched_job;
-		struct dma_fence *fence;
-		struct drm_sched_job *cleanup_job = NULL;
-
-		wait_event_interruptible(sched->wake_up_worker,
-					 (cleanup_job = drm_sched_get_cleanup_job(sched)) ||
-					 (!drm_sched_blocked(sched) &&
-					  (entity = drm_sched_select_entity(sched))) ||
-					 kthread_should_stop());
-
-		if (cleanup_job)
-			sched->ops->free_job(cleanup_job);
-
-		if (!entity)
-			continue;
-
-		sched_job = drm_sched_entity_pop_job(entity);
+	if (READ_ONCE(sched->pause_submit))
+		return;
 
-		if (!sched_job) {
-			complete_all(&entity->entity_idle);
-			continue;
-		}
+	/* Find entity with a ready job */
+	entity = drm_sched_select_entity(sched);
+	if (!entity)
+		return;	/* No more work */
 
-		s_fence = sched_job->s_fence;
+	sched_job = drm_sched_entity_pop_job(entity);
+	if (!sched_job) {
+		complete_all(&entity->entity_idle);
+		drm_sched_run_job_queue(sched);
+		return;
+	}
 
-		atomic_inc(&sched->hw_rq_count);
-		drm_sched_job_begin(sched_job);
+	s_fence = sched_job->s_fence;
 
-		trace_drm_run_job(sched_job, entity);
-		fence = sched->ops->run_job(sched_job);
-		complete_all(&entity->entity_idle);
-		drm_sched_fence_scheduled(s_fence, fence);
+	atomic_add(sched_job->credits, &sched->credit_count);
+	drm_sched_job_begin(sched_job);
 
-		if (!IS_ERR_OR_NULL(fence)) {
-			/* Drop for original kref_init of the fence */
-			dma_fence_put(fence);
+	trace_drm_run_job(sched_job, entity);
+	fence = sched->ops->run_job(sched_job);
+	complete_all(&entity->entity_idle);
+	drm_sched_fence_scheduled(s_fence, fence);
 
-			r = dma_fence_add_callback(fence, &sched_job->cb,
-						   drm_sched_job_done_cb);
-			if (r == -ENOENT)
-				drm_sched_job_done(sched_job, fence->error);
-			else if (r)
-				DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n",
-					  r);
-		} else {
-			drm_sched_job_done(sched_job, IS_ERR(fence) ?
-					   PTR_ERR(fence) : 0);
-		}
+	if (!IS_ERR_OR_NULL(fence)) {
+		/* Drop for original kref_init of the fence */
+		dma_fence_put(fence);
 
-		wake_up(&sched->job_scheduled);
+		r = dma_fence_add_callback(fence, &sched_job->cb,
+					   drm_sched_job_done_cb);
+		if (r == -ENOENT)
+			drm_sched_job_done(sched_job, fence->error);
+		else if (r)
+			DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n", r);
+	} else {
+		drm_sched_job_done(sched_job, IS_ERR(fence) ?
+				   PTR_ERR(fence) : 0);
 	}
-	return 0;
+
+	wake_up(&sched->job_scheduled);
+	drm_sched_run_job_queue(sched);
 }
 
 /**
@@ -1077,8 +1230,10 @@ static int drm_sched_main(void *param)
  *
  * @sched: scheduler instance
  * @ops: backend operations for this scheduler
+ * @submit_wq: workqueue to use for submission. If NULL, an ordered wq is
+ *	       allocated and used
  * @num_rqs: number of runqueues, one for each priority, up to DRM_SCHED_PRIORITY_COUNT
- * @hw_submission: number of hw submissions that can be in flight
+ * @credit_limit: the number of credits this scheduler can hold from all jobs
  * @hang_limit: number of times to allow a job to hang before dropping it
  * @timeout: timeout value in jiffies for the scheduler
  * @timeout_wq: workqueue to use for timeout work. If NULL, the system_wq is
@@ -1091,14 +1246,15 @@ static int drm_sched_main(void *param)
  */
 int drm_sched_init(struct drm_gpu_scheduler *sched,
 		   const struct drm_sched_backend_ops *ops,
-		   u32 num_rqs, uint32_t hw_submission, unsigned int hang_limit,
+		   struct workqueue_struct *submit_wq,
+		   u32 num_rqs, u32 credit_limit, unsigned int hang_limit,
 		   long timeout, struct workqueue_struct *timeout_wq,
 		   atomic_t *score, const char *name, struct device *dev)
 {
 	int i, ret;
 
 	sched->ops = ops;
-	sched->hw_submission_limit = hw_submission;
+	sched->credit_limit = credit_limit;
 	sched->name = name;
 	sched->timeout = timeout;
 	sched->timeout_wq = timeout_wq ? : system_wq;
@@ -1121,46 +1277,50 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
 		return 0;
 	}
 
+	if (submit_wq) {
+		sched->submit_wq = submit_wq;
+		sched->own_submit_wq = false;
+	} else {
+		sched->submit_wq = alloc_ordered_workqueue(name, 0);
+		if (!sched->submit_wq)
+			return -ENOMEM;
+
+		sched->own_submit_wq = true;
+	}
+	ret = -ENOMEM;
 	sched->sched_rq = kmalloc_array(num_rqs, sizeof(*sched->sched_rq),
 					GFP_KERNEL | __GFP_ZERO);
-	if (!sched->sched_rq) {
-		drm_err(sched, "%s: out of memory for sched_rq\n", __func__);
-		return -ENOMEM;
-	}
+	if (!sched->sched_rq)
+		goto Out_free;
 	sched->num_rqs = num_rqs;
-	ret = -ENOMEM;
-	for (i = DRM_SCHED_PRIORITY_MIN; i < sched->num_rqs; i++) {
+	for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) {
 		sched->sched_rq[i] = kzalloc(sizeof(*sched->sched_rq[i]), GFP_KERNEL);
 		if (!sched->sched_rq[i])
 			goto Out_unroll;
 		drm_sched_rq_init(sched, sched->sched_rq[i]);
 	}
 
-	init_waitqueue_head(&sched->wake_up_worker);
 	init_waitqueue_head(&sched->job_scheduled);
 	INIT_LIST_HEAD(&sched->pending_list);
 	spin_lock_init(&sched->job_list_lock);
-	atomic_set(&sched->hw_rq_count, 0);
+	atomic_set(&sched->credit_count, 0);
 	INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
+	INIT_WORK(&sched->work_run_job, drm_sched_run_job_work);
+	INIT_WORK(&sched->work_free_job, drm_sched_free_job_work);
 	atomic_set(&sched->_score, 0);
 	atomic64_set(&sched->job_id_count, 0);
-
-	/* Each scheduler will run on a seperate kernel thread */
-	sched->thread = kthread_run(drm_sched_main, sched, sched->name);
-	if (IS_ERR(sched->thread)) {
-		ret = PTR_ERR(sched->thread);
-		sched->thread = NULL;
-		DRM_DEV_ERROR(sched->dev, "Failed to create scheduler for %s.\n", name);
-		goto Out_unroll;
-	}
+	sched->pause_submit = false;
 
 	sched->ready = true;
 	return 0;
 Out_unroll:
-	for (--i ; i >= DRM_SCHED_PRIORITY_MIN; i--)
+	for (--i ; i >= DRM_SCHED_PRIORITY_KERNEL; i--)
 		kfree(sched->sched_rq[i]);
+Out_free:
 	kfree(sched->sched_rq);
 	sched->sched_rq = NULL;
+	if (sched->own_submit_wq)
+		destroy_workqueue(sched->submit_wq);
 	drm_err(sched, "%s: Failed to setup GPU scheduler--out of memory\n", __func__);
 	return ret;
 }
@@ -1178,10 +1338,9 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
 	struct drm_sched_entity *s_entity;
 	int i;
 
-	if (sched->thread)
-		kthread_stop(sched->thread);
+	drm_sched_wqueue_stop(sched);
 
-	for (i = sched->num_rqs - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
+	for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) {
 		struct drm_sched_rq *rq = sched->sched_rq[i];
 
 		spin_lock(&rq->lock);
@@ -1202,6 +1361,8 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
 	/* Confirm no work left behind accessing device structures */
 	cancel_delayed_work_sync(&sched->work_tdr);
 
+	if (sched->own_submit_wq)
+		destroy_workqueue(sched->submit_wq);
 	sched->ready = false;
 	kfree(sched->sched_rq);
 	sched->sched_rq = NULL;
@@ -1231,9 +1392,7 @@ void drm_sched_increase_karma(struct drm_sched_job *bad)
 	if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
 		atomic_inc(&bad->karma);
 
-		for (i = DRM_SCHED_PRIORITY_MIN;
-		     i < min_t(typeof(sched->num_rqs), sched->num_rqs, DRM_SCHED_PRIORITY_KERNEL);
-		     i++) {
+		for (i = DRM_SCHED_PRIORITY_HIGH; i < sched->num_rqs; i++) {
 			struct drm_sched_rq *rq = sched->sched_rq[i];
 
 			spin_lock(&rq->lock);
@@ -1252,3 +1411,42 @@ void drm_sched_increase_karma(struct drm_sched_job *bad)
 	}
 }
 EXPORT_SYMBOL(drm_sched_increase_karma);
+
+/**
+ * drm_sched_wqueue_ready - Is the scheduler ready for submission
+ *
+ * @sched: scheduler instance
+ *
+ * Returns true if submission is ready
+ */
+bool drm_sched_wqueue_ready(struct drm_gpu_scheduler *sched)
+{
+	return sched->ready;
+}
+EXPORT_SYMBOL(drm_sched_wqueue_ready);
+
+/**
+ * drm_sched_wqueue_stop - stop scheduler submission
+ *
+ * @sched: scheduler instance
+ */
+void drm_sched_wqueue_stop(struct drm_gpu_scheduler *sched)
+{
+	WRITE_ONCE(sched->pause_submit, true);
+	cancel_work_sync(&sched->work_run_job);
+	cancel_work_sync(&sched->work_free_job);
+}
+EXPORT_SYMBOL(drm_sched_wqueue_stop);
+
+/**
+ * drm_sched_wqueue_start - start scheduler submission
+ *
+ * @sched: scheduler instance
+ */
+void drm_sched_wqueue_start(struct drm_gpu_scheduler *sched)
+{
+	WRITE_ONCE(sched->pause_submit, false);
+	queue_work(sched->submit_wq, &sched->work_run_job);
+	queue_work(sched->submit_wq, &sched->work_free_job);
+}
+EXPORT_SYMBOL(drm_sched_wqueue_start);