drm/i915/selftests: Try to show where the pulse went

We have a case of a mysteriously absent pulse, so dump the engine
details to see if we can find out what happened to it.

References: https://bugs.freedesktop.org/show_bug.cgi?id=112405Signed-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/20191128102546.3857140-1-chris@chris-wilson.co.uk

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

@@ -1479,6 +1479,8 @@ void intel_engine_dump(struct intel_engine_cs *engine,
 		drm_printf(m, "*** WEDGED ***\n");
 
 	drm_printf(m, "\tAwake? %d\n", atomic_read(&engine->wakeref.count));
+	drm_printf(m, "\tBarriers?: %s\n",
+		   yesno(!llist_empty(&engine->barrier_tasks)));
 
 	rcu_read_lock();
 	rq = READ_ONCE(engine->heartbeat.systole);

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

@@ -91,6 +91,11 @@ static int __live_idle_pulse(struct intel_engine_cs *engine,
 	GEM_BUG_ON(!llist_empty(&engine->barrier_tasks));
 
 	if (intel_gt_retire_requests_timeout(engine->gt, HZ / 5)) {
+		struct drm_printer m = drm_err_printer("pulse");
+
+		pr_err("%s: no heartbeat pulse?\n", engine->name);
+		intel_engine_dump(engine, &m, "%s", engine->name);
+
 		err = -ETIME;
 		goto out;
 	}