This probably hasn't caused any problems up until now since it's probably nearly impossible to encounter this in the wild, however if we were to receive a connection status notification from the MST hub after resume while we're in the middle of reprobing the link addresses for a topology then there's a much larger chance that a port could have changed from being an output port to input port (or vice versa). If we forget to update this bit of information, we'll potentially ignore a valid PDT change on a downstream port because we think it's an input port.
So, make sure we read the input_port field in connection status notifications in drm_dp_mst_handle_conn_stat() to prevent this from happening once we've implemented suspend/resume reprobing.
Cc: Juston Li juston.li@intel.com Cc: Imre Deak imre.deak@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Harry Wentland hwentlan@amd.com Signed-off-by: Lyude Paul lyude@redhat.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 51 +++++++++++++++++++-------- 1 file changed, 37 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index dffd80f31537..126db36c9337 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1989,18 +1989,23 @@ static void drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb, struct drm_dp_connection_status_notify *conn_stat) { - struct drm_device *dev = mstb->mgr->dev; + struct drm_dp_mst_topology_mgr *mgr = mstb->mgr; + struct drm_device *dev = mgr->dev; struct drm_dp_mst_port *port; - int old_ddps; - bool dowork = false; + struct drm_connector *connector_to_destroy = NULL; + int old_ddps, ret; + u8 new_pdt; + bool dowork = false, create_connector = false;
port = drm_dp_get_port(mstb, conn_stat->port_number); if (!port) return;
+ mutex_lock(&port->lock); drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
old_ddps = port->ddps; + port->input = conn_stat->input_port; port->mcs = conn_stat->message_capability_status; port->ldps = conn_stat->legacy_device_plug_status; port->ddps = conn_stat->displayport_device_plug_status; @@ -2013,23 +2018,41 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb, } }
- if (!port->input) { - int ret = drm_dp_port_set_pdt(port, - conn_stat->peer_device_type); - if (ret == 1) { - dowork = true; - } else if (ret < 0) { - DRM_ERROR("Failed to change PDT for port %p: %d\n", - port, ret); - dowork = false; - } + new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat->peer_device_type; + + ret = drm_dp_port_set_pdt(port, new_pdt); + if (ret == 1) { + dowork = true; + } else if (ret < 0) { + DRM_ERROR("Failed to change PDT for port %p: %d\n", + port, ret); + dowork = false; + } + + /* + * We unset port->connector before dropping connection_mutex so that + * there's no chance any of the atomic MST helpers can accidentally + * associate a to-be-destroyed connector with a port. + */ + if (port->connector && port->input) { + connector_to_destroy = port->connector; + port->connector = NULL; + } else if (!port->connector && !port->input) { + create_connector = true; }
drm_modeset_unlock(&dev->mode_config.connection_mutex); + + if (connector_to_destroy) + mgr->cbs->destroy_connector(mgr, connector_to_destroy); + else if (create_connector) + drm_dp_mst_port_add_connector(mstb, port); + + mutex_unlock(&port->lock); + drm_dp_mst_topology_put_port(port); if (dowork) queue_work(system_long_wq, &mstb->mgr->work); - }
static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,