drm/sched: Add basic priority tests

Add some basic tests for exercising entity priority handling.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <phasta@kernel.org>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250324092633.49746-5-tvrtko.ursulin@igalia.com

drivers/gpu/drm/scheduler/tests/tests_basic.c

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2025 Valve Corporation */
 
+#include <linux/delay.h>
+
 #include "sched_tests.h"
 
 /*
@@ -254,5 +256,96 @@ static struct kunit_suite drm_sched_timeout = {
 	.test_cases = drm_sched_timeout_tests,
 };
 
+static void drm_sched_priorities(struct kunit *test)
+{
+	struct drm_mock_sched_entity *entity[DRM_SCHED_PRIORITY_COUNT];
+	struct drm_mock_scheduler *sched = test->priv;
+	struct drm_mock_sched_job *job;
+	const unsigned int qd = 100;
+	unsigned int i, cur_ent = 0;
+	enum drm_sched_priority p;
+	bool done;
+
+	/*
+	 * Submit a bunch of jobs against entities configured with different
+	 * priorities.
+	 */
+
+	BUILD_BUG_ON(DRM_SCHED_PRIORITY_KERNEL > DRM_SCHED_PRIORITY_LOW);
+	BUILD_BUG_ON(ARRAY_SIZE(entity) != DRM_SCHED_PRIORITY_COUNT);
+
+	for (p = DRM_SCHED_PRIORITY_KERNEL; p <= DRM_SCHED_PRIORITY_LOW; p++)
+		entity[p] = drm_mock_sched_entity_new(test, p, sched);
+
+	for (i = 0; i < qd; i++) {
+		job = drm_mock_sched_job_new(test, entity[cur_ent++]);
+		cur_ent %= ARRAY_SIZE(entity);
+		drm_mock_sched_job_set_duration_us(job, 1000);
+		drm_mock_sched_job_submit(job);
+	}
+
+	done = drm_mock_sched_job_wait_finished(job, HZ);
+	KUNIT_ASSERT_TRUE(test, done);
+
+	for (i = 0; i < ARRAY_SIZE(entity); i++)
+		drm_mock_sched_entity_free(entity[i]);
+}
+
+static void drm_sched_change_priority(struct kunit *test)
+{
+	struct drm_mock_sched_entity *entity[DRM_SCHED_PRIORITY_COUNT];
+	struct drm_mock_scheduler *sched = test->priv;
+	struct drm_mock_sched_job *job;
+	const unsigned int qd = 1000;
+	unsigned int i, cur_ent = 0;
+	enum drm_sched_priority p;
+
+	/*
+	 * Submit a bunch of jobs against entities configured with different
+	 * priorities and while waiting for them to complete, periodically keep
+	 * changing their priorities.
+	 *
+	 * We set up the queue-depth (qd) and job duration so the priority
+	 * changing loop has some time to interact with submissions to the
+	 * backend and job completions as they progress.
+	 */
+
+	for (p = DRM_SCHED_PRIORITY_KERNEL; p <= DRM_SCHED_PRIORITY_LOW; p++)
+		entity[p] = drm_mock_sched_entity_new(test, p, sched);
+
+	for (i = 0; i < qd; i++) {
+		job = drm_mock_sched_job_new(test, entity[cur_ent++]);
+		cur_ent %= ARRAY_SIZE(entity);
+		drm_mock_sched_job_set_duration_us(job, 1000);
+		drm_mock_sched_job_submit(job);
+	}
+
+	do {
+		drm_sched_entity_set_priority(&entity[cur_ent]->base,
+					      (entity[cur_ent]->base.priority + 1) %
+					      DRM_SCHED_PRIORITY_COUNT);
+		cur_ent++;
+		cur_ent %= ARRAY_SIZE(entity);
+		usleep_range(200, 500);
+	} while (!drm_mock_sched_job_is_finished(job));
+
+	for (i = 0; i < ARRAY_SIZE(entity); i++)
+		drm_mock_sched_entity_free(entity[i]);
+}
+
+static struct kunit_case drm_sched_priority_tests[] = {
+	KUNIT_CASE(drm_sched_priorities),
+	KUNIT_CASE(drm_sched_change_priority),
+	{}
+};
+
+static struct kunit_suite drm_sched_priority = {
+	.name = "drm_sched_basic_priority_tests",
+	.init = drm_sched_basic_init,
+	.exit = drm_sched_basic_exit,
+	.test_cases = drm_sched_priority_tests,
+};
+
 kunit_test_suites(&drm_sched_basic,
-		  &drm_sched_timeout);
+		  &drm_sched_timeout,
+		  &drm_sched_priority);