drm/i915: Show the execlist queue in debugfs/i915_engine_info

When looking at freezes whilst working on execlists, knowing the order
of the pending requests in the driver is useful.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161027000348.4641-2-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -3255,6 +3255,12 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 			else
 				seq_printf(m, "\t\tELSP[1] idle\n");
 			rcu_read_unlock();
+
+			spin_lock_irq(&engine->execlist_lock);
+			list_for_each_entry(rq, &engine->execlist_queue, execlist_link) {
+				print_request(m, rq, "\t\tQ ");
+			}
+			spin_unlock_irq(&engine->execlist_lock);
 		} else if (INTEL_GEN(dev_priv) > 6) {
 			seq_printf(m, "\tPP_DIR_BASE: 0x%08x\n",
 				   I915_READ(RING_PP_DIR_BASE(engine)));