drm/sched: implement and export drm_sched_pick_best

Remove drm_sched_entity_get_free_sched() and use the logic of picking
the least loaded drm scheduler from a drm scheduler list to implement
drm_sched_pick_best(). This patch also exports drm_sched_pick_best() so
that it can be utilized by other drm drivers.

Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/scheduler/sched_entity.c

@@ -137,38 +137,6 @@ bool drm_sched_entity_is_ready(struct drm_sched_entity *entity)
 	return true;
 }
 
-/**
- * drm_sched_entity_get_free_sched - Get the rq from rq_list with least load
- *
- * @entity: scheduler entity
- *
- * Return the pointer to the rq with least load.
- */
-static struct drm_sched_rq *
-drm_sched_entity_get_free_sched(struct drm_sched_entity *entity)
-{
-	struct drm_sched_rq *rq = NULL;
-	unsigned int min_jobs = UINT_MAX, num_jobs;
-	int i;
-
-	for (i = 0; i < entity->num_sched_list; ++i) {
-		struct drm_gpu_scheduler *sched = entity->sched_list[i];
-
-		if (!entity->sched_list[i]->ready) {
-			DRM_WARN("sched%s is not ready, skipping", sched->name);
-			continue;
-		}
-
-		num_jobs = atomic_read(&sched->num_jobs);
-		if (num_jobs < min_jobs) {
-			min_jobs = num_jobs;
-			rq = &entity->sched_list[i]->sched_rq[entity->priority];
-		}
-	}
-
-	return rq;
-}
-
 /**
  * drm_sched_entity_flush - Flush a context entity
  *
@@ -479,6 +447,7 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
 void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
 {
 	struct dma_fence *fence;
+	struct drm_gpu_scheduler *sched;
 	struct drm_sched_rq *rq;
 
 	if (spsc_queue_count(&entity->job_queue) || entity->num_sched_list <= 1)
@@ -489,7 +458,8 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
 		return;
 
 	spin_lock(&entity->rq_lock);
-	rq = drm_sched_entity_get_free_sched(entity);
+	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
+	rq = sched ? &sched->sched_rq[entity->priority] : NULL;
 	if (rq != entity->rq) {
 		drm_sched_rq_remove_entity(entity->rq, entity);
 		entity->rq = rq;

drivers/gpu/drm/scheduler/sched_main.c

@@ -696,6 +696,42 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
 	return job;
 }
 
+/**
+ * drm_sched_pick_best - Get a drm sched from a sched_list with the least load
+ * @sched_list: list of drm_gpu_schedulers
+ * @num_sched_list: number of drm_gpu_schedulers in the sched_list
+ *
+ * Returns pointer of the sched with the least load or NULL if none of the
+ * drm_gpu_schedulers are ready
+ */
+struct drm_gpu_scheduler *
+drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
+		     unsigned int num_sched_list)
+{
+	struct drm_gpu_scheduler *sched, *picked_sched = NULL;
+	int i;
+	unsigned int min_jobs = UINT_MAX, num_jobs;
+
+	for (i = 0; i < num_sched_list; ++i) {
+		sched = sched_list[i];
+
+		if (!sched->ready) {
+			DRM_WARN("scheduler %s is not ready, skipping",
+				 sched->name);
+			continue;
+		}
+
+		num_jobs = atomic_read(&sched->num_jobs);
+		if (num_jobs < min_jobs) {
+			min_jobs = num_jobs;
+			picked_sched = sched;
+		}
+	}
+
+	return picked_sched;
+}
+EXPORT_SYMBOL(drm_sched_pick_best);
+
 /**
  * drm_sched_blocked - check if the scheduler is blocked
  *

include/drm/gpu_scheduler.h

@@ -341,5 +341,8 @@ void drm_sched_fence_finished(struct drm_sched_fence *fence);
 unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched);
 void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
 		                unsigned long remaining);
+struct drm_gpu_scheduler *
+drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
+		     unsigned int num_sched_list);
 
 #endif