drm/dp_mst: Don't forget to update port->input in drm_dp_mst_handle_conn_stat()

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>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191022023641.8026-8-lyude@redhat.com

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 55f289e..5e031b0 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2079,18 +2079,38 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
 {
        struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
        struct drm_dp_mst_port *port;
-       int old_ddps;
-       bool dowork = false;
+       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;
 
-       /* Locking is only needed if the port's exposed to userspace */
-       if (port->connector)
+       if (port->connector) {
+               if (!port->input && conn_stat->input_port) {
+                       /*
+                        * We can't remove a connector from an already exposed
+                        * port, so just throw the port out and make sure we
+                        * reprobe the link address of it's parent MSTB
+                        */
+                       drm_dp_mst_topology_unlink_port(mgr, port);
+                       mstb->link_address_sent = false;
+                       dowork = true;
+                       goto out;
+               }
+
+               /* Locking is only needed if the port's exposed to userspace */
                drm_modeset_lock(&mgr->base.lock, NULL);
+       } else if (port->input && !conn_stat->input_port) {
+               create_connector = true;
+               /* Reprobe link address so we get num_sdp_streams */
+               mstb->link_address_sent = false;
+               dowork = true;
+       }
 
        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;
@@ -2103,21 +2123,23 @@ 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;
        }
 
        if (port->connector)
                drm_modeset_unlock(&mgr->base.lock);
+       else if (create_connector)
+               drm_dp_mst_port_add_connector(mstb, port);
 
+out:
        drm_dp_mst_topology_put_port(port);
        if (dowork)
                queue_work(system_long_wq, &mstb->mgr->work);