drm/i915/gt: Include a tell-tale for engine parking

We have two trace messages that rely on the function name for
distinction. However, if gcc inlines the function, the two traces end up
with the same function name and are indistinguishable. Add a different
message to each to clarify which one we hit, i.e. which phase of engine
parking we are processing.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200122124154.483444-1-chris@chris-wilson.co.uk

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

@@ -112,7 +112,7 @@ __queue_and_release_pm(struct i915_request *rq,
 {
 	struct intel_gt_timelines *timelines = &engine->gt->timelines;
 
-	ENGINE_TRACE(engine, "\n");
+	ENGINE_TRACE(engine, "parking\n");
 
 	/*
 	 * We have to serialise all potential retirement paths with our
@@ -249,7 +249,7 @@ static int __engine_park(struct intel_wakeref *wf)
 	if (!switch_to_kernel_context(engine))
 		return -EBUSY;
 
-	ENGINE_TRACE(engine, "\n");
+	ENGINE_TRACE(engine, "parked\n");
 
 	call_idle_barriers(engine); /* cleanup after wedging */