drm/i915: Add i915_sched_engine_is_empty function

Add wrapper function around RB tree to determine if i915_sched_engine is
empty.
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210618010638.98941-3-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -1259,7 +1259,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
 	intel_engine_flush_submission(engine);
 
 	/* ELSP is empty, but there are ready requests? E.g. after reset */
-	if (!RB_EMPTY_ROOT(&engine->sched_engine->queue.rb_root))
+	if (!i915_sched_engine_is_empty(engine->sched_engine))
 		return false;
 
 	/* Ring stopped? */

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

@@ -384,7 +384,7 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
 			prio = rq_prio(rq);
 			pl = i915_sched_lookup_priolist(engine, prio);
 		}
-		GEM_BUG_ON(RB_EMPTY_ROOT(&engine->sched_engine->queue.rb_root));
+		GEM_BUG_ON(i915_sched_engine_is_empty(engine->sched_engine));
 
 		list_move(&rq->sched.link, pl);
 		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
@@ -1139,7 +1139,7 @@ static bool needs_timeslice(const struct intel_engine_cs *engine,
 	}
 
 	/* Otherwise, ELSP[0] is by itself, but may be waiting in the queue */
-	if (!RB_EMPTY_ROOT(&engine->sched_engine->queue.rb_root)) {
+	if (!i915_sched_engine_is_empty(engine->sched_engine)) {
 		ENGINE_TRACE(engine, "timeslice required for queue\n");
 		return true;
 	}
@@ -2487,7 +2487,7 @@ static void execlists_submit_request(struct i915_request *request)
 	} else {
 		queue_request(engine, request);
 
-		GEM_BUG_ON(RB_EMPTY_ROOT(&engine->sched_engine->queue.rb_root));
+		GEM_BUG_ON(i915_sched_engine_is_empty(engine->sched_engine));
 		GEM_BUG_ON(list_empty(&request->sched.link));
 
 		if (submit_queue(engine, request))

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -515,7 +515,7 @@ static void guc_submit_request(struct i915_request *rq)
 
 	queue_request(engine, rq, rq_prio(rq));
 
-	GEM_BUG_ON(RB_EMPTY_ROOT(&engine->sched_engine->queue.rb_root));
+	GEM_BUG_ON(i915_sched_engine_is_empty(engine->sched_engine));
 	GEM_BUG_ON(list_empty(&rq->sched.link));
 
 	tasklet_hi_schedule(&engine->execlists.tasklet);

drivers/gpu/drm/i915/i915_scheduler.h

@@ -66,6 +66,12 @@ i915_sched_engine_put(struct i915_sched_engine *sched_engine)
 	kref_put(&sched_engine->ref, i915_sched_engine_free);
 }
 
+static inline bool
+i915_sched_engine_is_empty(struct i915_sched_engine *sched_engine)
+{
+	return RB_EMPTY_ROOT(&sched_engine->queue.rb_root);
+}
+
 void i915_request_show_with_schedule(struct drm_printer *m,
 				     const struct i915_request *rq,
 				     const char *prefix,