drm/sched: Reverse run-queue priority enumeration

Reverse run-queue priority enumeration such that the higest priority is now 0,
and for each consecutive integer the prioirty diminishes.

Run-queues correspond to priorities. To an external observer a scheduler
created with a single run-queue, and another created with
DRM_SCHED_PRIORITY_COUNT number of run-queues, should always schedule
sched->sched_rq[0] with the same "priority", as that index run-queue exists in
both schedulers, i.e. a scheduler with one run-queue or many. This patch makes
it so.

In other words, the "priority" of sched->sched_rq[n], n >= 0, is the same for
any scheduler created with any allowable number of run-queues (priorities), 0
to DRM_SCHED_PRIORITY_COUNT.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Luben Tuikov <ltuikov89@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231124052752.6915-6-ltuikov89@gmail.com

1 files changed, 7 insertions, 8 deletions

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index b6d7bc49ff6e..682aebe96db7 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -1051,8 +1051,9 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 	struct drm_sched_entity *entity;
 	int i;
 
-	/* Kernel run queue has higher priority than normal run queue*/
-	for (i = sched->num_rqs - 1; i >= DRM_SCHED_PRIORITY_LOW; 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->sched_rq[i]) :
 			drm_sched_rq_select_entity_rr(sched, sched->sched_rq[i]);
@@ -1291,7 +1292,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
 	if (!sched->sched_rq)
 		goto Out_free;
 	sched->num_rqs = num_rqs;
-	for (i = DRM_SCHED_PRIORITY_LOW; 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;
@@ -1312,7 +1313,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
 	sched->ready = true;
 	return 0;
 Out_unroll:
-	for (--i ; i >= DRM_SCHED_PRIORITY_LOW; i--)
+	for (--i ; i >= DRM_SCHED_PRIORITY_KERNEL; i--)
 		kfree(sched->sched_rq[i]);
 Out_free:
 	kfree(sched->sched_rq);
@@ -1338,7 +1339,7 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
 
 	drm_sched_wqueue_stop(sched);
 
-	for (i = sched->num_rqs - 1; i >= DRM_SCHED_PRIORITY_LOW; 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);
@@ -1390,9 +1391,7 @@ 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_LOW;
-		     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);