[PATCH 70/80] defer

[Chris Wilson]

---
 drivers/gpu/drm/i915/gt/intel_lrc.c   | 55 ++++-----------------------
 drivers/gpu/drm/i915/i915_scheduler.c | 52 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_scheduler.h |  3 ++
 3 files changed, 62 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 1c15398932d0..51ab7e7780cc 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1826,9 +1826,13 @@ static void virtual_xfer_context(struct virtual_engine *ve,
 	}
 }
 
-static void defer_request(struct i915_request *rq, struct list_head * const pl)
+static void defer_active(struct intel_engine_cs *engine)
 {
-	LIST_HEAD(list);
+	struct i915_request *rq;
+
+	rq = __unwind_incomplete_requests(engine);
+	if (!rq)
+		return;
 
 	/*
 	 * We want to move the interrupted request to the back of
@@ -1837,52 +1841,7 @@ static void defer_request(struct i915_request *rq, struct list_head * const pl)
 	 * flight and were waiting for the interrupted request to
 	 * be run after it again.
 	 */
-	do {
-		struct i915_dependency *p;
-
-		GEM_BUG_ON(i915_request_is_active(rq));
-		list_move_tail(&rq->sched.link, pl);
-
-		for_each_waiter(p, rq) {
-			struct i915_request *w =
-				container_of(p->waiter, typeof(*w), sched);
-
-			if (!p->waiter || p->flags & I915_DEPENDENCY_WEAK)
-				continue;
-
-			/* Leave semaphores spinning on the other engines */
-			if (w->engine != rq->engine)
-				continue;
-
-			/* No waiter should start before its signaler */
-			GEM_BUG_ON(i915_request_has_initial_breadcrumb(w) &&
-				   i915_request_started(w) &&
-				   !i915_request_completed(rq));
-
-			GEM_BUG_ON(i915_request_is_active(w));
-			if (!i915_request_is_ready(w))
-				continue;
-
-			if (rq_prio(w) < rq_prio(rq))
-				continue;
-
-			GEM_BUG_ON(rq_prio(w) > rq_prio(rq));
-			list_move_tail(&w->sched.link, &list);
-		}
-
-		rq = list_first_entry_or_null(&list, typeof(*rq), sched.link);
-	} while (rq);
-}
-
-static void defer_active(struct intel_engine_cs *engine)
-{
-	struct i915_request *rq;
-
-	rq = __unwind_incomplete_requests(engine);
-	if (!rq)
-		return;
-
-	defer_request(rq, i915_sched_lookup_priolist(engine, rq_prio(rq)));
+	__intel_engine_defer_request(engine, rq);
 }
 
 static bool
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 7873f366b078..006965a1a51a 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -463,6 +463,58 @@ void i915_request_set_priority(struct i915_request *rq, int prio)
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
 
+void __intel_engine_defer_request(struct intel_engine_cs *engine,
+				  struct i915_request *rq)
+{
+	struct list_head *pl;
+	LIST_HEAD(list);
+
+	lockdep_assert_held(&engine->active.lock);
+	GEM_BUG_ON(!test_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags));
+
+	/*
+	 * When we defer a request, we must maintain its order with respect
+	 * to those that are waiting upon it. So we traverse its chain of
+	 * waiters and move any that are earlier than the request to after it.
+	 */
+	pl = i915_sched_lookup_priolist(engine, rq_prio(rq));
+	do {
+		struct i915_dependency *p;
+
+		GEM_BUG_ON(i915_request_is_active(rq));
+		list_move_tail(&rq->sched.link, pl);
+
+		for_each_waiter(p, rq) {
+			struct i915_request *w =
+				container_of(p->waiter, typeof(*w), sched);
+
+			if (!p->waiter || p->flags & I915_DEPENDENCY_WEAK)
+				continue;
+
+			/* Leave semaphores spinning on the other engines */
+			if (w->engine != engine)
+				continue;
+
+			/* No waiter should start before its signaler */
+			GEM_BUG_ON(i915_request_has_initial_breadcrumb(w) &&
+				   i915_request_started(w) &&
+				   !i915_request_completed(rq));
+
+			GEM_BUG_ON(i915_request_is_active(w));
+			if (!i915_request_is_ready(w))
+				continue;
+
+			if (rq_prio(w) < rq_prio(rq))
+				continue;
+
+			GEM_BUG_ON(rq_prio(w) > rq_prio(rq));
+			list_move_tail(&w->sched.link, &list);
+		}
+
+		rq = list_first_entry_or_null(&list, typeof(*rq), sched.link);
+	} while (rq);
+}
+
 static void queue_request(struct intel_engine_cs *engine,
 			  struct i915_request *rq)
 {
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index 1a8b9b6cc2eb..ef67cadc03e3 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -37,6 +37,9 @@ void i915_request_set_priority(struct i915_request *request, int prio);
 
 void i915_request_enqueue(struct i915_request *request);
 
+void __intel_engine_defer_request(struct intel_engine_cs *engine,
+				  struct i915_request *request);
+
 bool __intel_engine_hold_request(struct intel_engine_cs *engine,
 				 struct i915_request *request);
 void __intel_engine_unhold_request(struct intel_engine_cs *engine,
-- 
2.20.1