drm/i915/selftests: Pretty print the i915_active

If the idle_pulse fails to flush the i915_active, dump the tree to see
if that has any clues.

Signed-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/20191031101116.19894-1-chris@chris-wilson.co.uk

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

@@ -102,8 +102,12 @@ static int __live_idle_pulse(struct intel_engine_cs *engine,
 	pulse_unlock_wait(p); /* synchronize with the retirement callback */
 
 	if (!i915_active_is_idle(&p->active)) {
+		struct drm_printer m = drm_err_printer("pulse");
+
 		pr_err("%s: heartbeat pulse did not flush idle tasks\n",
 		       engine->name);
+		i915_active_print(&p->active, &m);
+
 		err = -EINVAL;
 		goto out;
 	}

drivers/gpu/drm/i915/i915_active.h

@@ -214,4 +214,6 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 void i915_active_acquire_barrier(struct i915_active *ref);
 void i915_request_add_active_barriers(struct i915_request *rq);
 
+void i915_active_print(struct i915_active *ref, struct drm_printer *m);
+
 #endif /* _I915_ACTIVE_H_ */

drivers/gpu/drm/i915/selftests/i915_active.c

@@ -205,3 +205,48 @@ int i915_active_live_selftests(struct drm_i915_private *i915)
 
 	return i915_subtests(tests, i915);
 }
+
+static struct intel_engine_cs *node_to_barrier(struct active_node *it)
+{
+	struct intel_engine_cs *engine;
+
+	if (!is_barrier(&it->base))
+		return NULL;
+
+	engine = __barrier_to_engine(it);
+	smp_rmb(); /* serialise with add_active_barriers */
+	if (!is_barrier(&it->base))
+		return NULL;
+
+	return engine;
+}
+
+void i915_active_print(struct i915_active *ref, struct drm_printer *m)
+{
+	drm_printf(m, "active %pS:%pS\n", ref->active, ref->retire);
+	drm_printf(m, "\tcount: %d\n", atomic_read(&ref->count));
+	drm_printf(m, "\tpreallocated barriers? %s\n",
+		   yesno(!llist_empty(&ref->preallocated_barriers)));
+
+	if (i915_active_acquire_if_busy(ref)) {
+		struct active_node *it, *n;
+
+		rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
+			struct intel_engine_cs *engine;
+
+			engine = node_to_barrier(it);
+			if (engine) {
+				drm_printf(m, "\tbarrier: %s\n", engine->name);
+				continue;
+			}
+
+			if (i915_active_fence_isset(&it->base)) {
+				drm_printf(m,
+					   "\ttimeline: %llx\n", it->timeline);
+				continue;
+			}
+		}
+
+		i915_active_release(ref);
+	}
+}