drm/i915/execlists: Mark up expected state during reset

Move the BUG_ON around slightly and add some explanations for each to
try and capture the expected state more carefully. We want to compare
the expected active state of our bookkeeping as compared to the tracked
HW state.

References: https://bugs.freedesktop.org/show_bug.cgi?id=111937Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191010083242.1387-1-chris@chris-wilson.co.uk

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

@@ -2728,8 +2728,10 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	if (!rq)
 		goto unwind;
 
+	/* We still have requests in-flight; the engine should be active */
+	GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
+
 	ce = rq->hw_context;
-	GEM_BUG_ON(i915_active_is_idle(&ce->active));
 	GEM_BUG_ON(!i915_vma_is_pinned(ce->state));
 
 	/* Proclaim we have exclusive access to the context image! */
@@ -2737,10 +2739,13 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 
 	rq = active_request(rq);
 	if (!rq) {
+		/* Idle context; tidy up the ring so we can restart afresh */
 		ce->ring->head = ce->ring->tail;
 		goto out_replay;
 	}
 
+	/* Context has requests still in-flight; it should not be idle! */
+	GEM_BUG_ON(i915_active_is_idle(&ce->active));
 	ce->ring->head = intel_ring_wrap(ce->ring, rq->head);
 
 	/*