[Why] Now, after receiving CSN notifying that a port is disconnected, we can unregister child connectors under a branch device via drm_dp_mst_topology_put_mstb() in drm_dp_port_set_pdt(). However, if this reported disconnected port is used to connect to an end device(sst/dp_to_legace converter), we won't unregiser such connector.

[How] Take sst/dp_to_legacy conveter device into consideration, also unregister connectors of this case when handling CSN.

In addition, check whether port->connector exist to avoid null pointer dereference.

Cc: stable@vger.kernel.org Signed-off-by: Wayne Lin Wayne.Lin@amd.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index f13c7187b07f..85a959427247 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2567,6 +2567,12 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb, else if (create_connector) drm_dp_mst_port_add_connector(mstb, port);

+ if (port->connector && port->pdt == DP_PEER_DEVICE_NONE) { + drm_connector_unregister(port->connector); + drm_connector_put(port->connector); + port->connector = NULL; + } + out: drm_dp_mst_topology_put_port(port); if (dowork) @@ -4442,10 +4448,12 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state, req_slots = DIV_ROUND_UP(pbn, pbn_div);

drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n", - port->connector->base.id, port->connector->name, + port->connector ? port->connector->base.id : 0, + port->connector ? port->connector->name : "NULL", port, prev_slots, req_slots); drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n", - port->connector->base.id, port->connector->name, + port->connector ? port->connector->base.id : 0, + port->connector ? port->connector->name : "NULL", port, prev_bw, pbn);

/* Add the new allocation to the state */