From: Andrey Grodzovsky <andrey.grodzov...@amd.com>

On DELL U3014 if you clear the table before enabling MST it sometimes
hangs the receiver.

Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky at amd.com>
Reviewed-by: Harry Wentland <harry.wentland at amd.com>
Acked-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c 
b/drivers/gpu/drm/drm_dp_mst_topology.c
index 01a7d0198e15..fc589265068b 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1998,6 +1998,12 @@ int drm_dp_mst_topology_mgr_set_mst(struct 
drm_dp_mst_topology_mgr *mgr, bool ms
                mgr->mst_primary = mstb;
                kref_get(&mgr->mst_primary->kref);

+               ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
+                                                        DP_MST_EN | 
DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC);
+               if (ret < 0) {
+                       goto out_unlock;
+               }
+
                {
                        struct drm_dp_payload reset_pay;
                        reset_pay.start_slot = 0;
@@ -2005,12 +2011,6 @@ int drm_dp_mst_topology_mgr_set_mst(struct 
drm_dp_mst_topology_mgr *mgr, bool ms
                        drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
                }

-               ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
-                                        DP_MST_EN | DP_UP_REQ_EN | 
DP_UPSTREAM_IS_SRC);
-               if (ret < 0) {
-                       goto out_unlock;
-               }
-
                queue_work(system_long_wq, &mgr->work);

                ret = 0;
-- 
2.1.4

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