[PATCH v1] drm/radeon: Fix a missing check bug in radeon_dp_mst_detect()

[wangyingjie55 at 126.com]

From: Yingjie Wang <wangyingjie55 at 126.com>

In radeon_dp_mst_detect(), We should check whether or not @connector
has been unregistered from userspace. If the connector is unregistered,
we should return disconnected status.

Fixes: 9843ead08f18 ("drm/radeon: add DisplayPort MST support (v2)")
Signed-off-by: Yingjie Wang <wangyingjie55 at 126.com>
---
 drivers/gpu/drm/radeon/radeon_dp_mst.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c b/drivers/gpu/drm/radeon/radeon_dp_mst.c
index 2c32186c4acd..4e4c937c36c6 100644
--- a/drivers/gpu/drm/radeon/radeon_dp_mst.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c
@@ -242,6 +242,9 @@ radeon_dp_mst_detect(struct drm_connector *connector,
 		to_radeon_connector(connector);
 	struct radeon_connector *master = radeon_connector->mst_port;
 
+	if (drm_connector_is_unregistered(connector))
+		return connector_status_disconnected;
+
 	return drm_dp_mst_detect_port(connector, ctx, &master->mst_mgr,
 				      radeon_connector->port);
 }
-- 
2.7.4