[PATCH v5 07/14] drm/dp_mst: Don't forget to update port->input in drm_dp_mst_handle_conn_stat()

Lyude Paul
2019-10-22T02:36:02Z

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>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 52 +++++++++++++++++++--------
1 file changed, 38 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 7bf4db91ff90..c8e218b902ae 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2079,18 +2079,40 @@ 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 +2125,23 @@ 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);
--
2.21.0