drm/sched: Convert the GPU scheduler to variable number of run-queues

The GPU scheduler has now a variable number of run-queues, which are set up at
drm_sched_init() time. This way, each driver announces how many run-queues it
requires (supports) per each GPU scheduler it creates. Note, that run-queues
correspond to scheduler "priorities", thus if the number of run-queues is set
to 1 at drm_sched_init(), then that scheduler supports a single run-queue,
i.e. single "priority". If a driver further sets a single entity per
run-queue, then this creates a 1-to-1 correspondence between a scheduler and
a scheduled entity.

Cc: Lucas Stach <[email protected]>
Cc: Russell King <[email protected]>
Cc: Qiang Yu <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Danilo Krummrich <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: Christian König <[email protected]>
Cc: Emma Anholt <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Luben Tuikov <[email protected]>
Acked-by: Christian König <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index a42763e1429d..409e4256f6e7 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -75,8 +75,20 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
 	RCU_INIT_POINTER(entity->last_scheduled, NULL);
 	RB_CLEAR_NODE(&entity->rb_tree_node);
 
-	if(num_sched_list)
-		entity->rq = &sched_list[0]->sched_rq[entity->priority];
+	if (!sched_list[0]->sched_rq) {
+		/* Warn drivers not to do this and to fix their DRM
+		 * calling order.
+		 */
+		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.
+		 */
+		if (entity->priority >= sched_list[0]->num_rqs)
+			entity->priority = max_t(u32, sched_list[0]->num_rqs,
+						 DRM_SCHED_PRIORITY_MIN);
+		entity->rq = sched_list[0]->sched_rq[entity->priority];
+	}
 
 	init_completion(&entity->entity_idle);
 
@@ -533,7 +545,7 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
 
 	spin_lock(&entity->rq_lock);
 	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
-	rq = sched ? &sched->sched_rq[entity->priority] : NULL;
+	rq = sched ? sched->sched_rq[entity->priority] : NULL;
 	if (rq != entity->rq) {
 		drm_sched_rq_remove_entity(entity->rq, entity);
 		entity->rq = rq;