drm/i915: Ignore submit-fences on the same timeline

While we ordinarily do not skip submit-fences due to the accompanying
hook that we want to callback on execution, a submit-fence on the same
timeline is meaningless.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200508092933.738-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_request.c

@@ -1242,6 +1242,9 @@ i915_request_await_execution(struct i915_request *rq,
 			continue;
 		}
 
+		if (fence->context == rq->fence.context)
+			continue;
+
 		/*
 		 * We don't squash repeated fence dependencies here as we
 		 * want to run our callback in all cases.