drm_dp_mst_topology_mgr_resume() returns whether or not it managed to find the topology in question after a suspend resume cycle, and the driver is supposed to check this value and disable MST accordingly if it's gone-in addition to sending a hotplug in order to notify userspace that something changed during suspend.

Currently, amdgpu just makes the mistake of ignoring the return code from drm_dp_mst_topology_mgr_resume() which means that if a topology was removed in suspend, amdgpu never notices and assumes it's still connected which leads to all sorts of problems.

So, fix this by actually checking the rc from drm_dp_mst_topology_mgr_resume(). Also, reformat the rest of the function while we're at it to fix the over-indenting.

Signed-off-by: Lyude Paul lyude@redhat.com Cc: Jerry Zuo Jerry.Zuo@amd.com Cc: stable@vger.kernel.org # v4.15+ --- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 32 +++++++++++++------ 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 8a626d16e8e3..3f326a2c513b 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -699,22 +699,36 @@ static void s3_handle_mst(struct drm_device *dev, bool suspend) { struct amdgpu_dm_connector *aconnector; struct drm_connector *connector; + struct drm_dp_mst_topology_mgr *mgr; + int ret; + bool need_hotplug = false;

drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);

- list_for_each_entry(connector, &dev->mode_config.connector_list, head) { - aconnector = to_amdgpu_dm_connector(connector); - if (aconnector->dc_link->type == dc_connection_mst_branch && - !aconnector->mst_port) { + list_for_each_entry(connector, &dev->mode_config.connector_list, + head) { + aconnector = to_amdgpu_dm_connector(connector); + if (aconnector->dc_link->type != dc_connection_mst_branch || + aconnector->mst_port) + continue; + + mgr = &aconnector->mst_mgr;

- if (suspend) - drm_dp_mst_topology_mgr_suspend(&aconnector->mst_mgr); - else - drm_dp_mst_topology_mgr_resume(&aconnector->mst_mgr); - } + if (suspend) { + drm_dp_mst_topology_mgr_suspend(mgr); + } else { + ret = drm_dp_mst_topology_mgr_resume(mgr); + if (ret < 0) { + drm_dp_mst_topology_mgr_set_mst(mgr, false); + need_hotplug = true; + } + } }

drm_modeset_unlock(&dev->mode_config.connection_mutex); + + if (need_hotplug) + drm_kms_helper_hotplug_event(dev); }

/**