From: Lyude <cpaul@xxxxxxxxxx> This patch has been added to the 4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 9e60290dbafdf577766e5fc5f2fdb3be450cf9a6 ] After unplugging a DP MST display from the system, we have to go through and destroy all of the DRM connectors associated with it since none of them are valid anymore. Unfortunately, intel_dp_destroy_mst_connector() doesn't do a good enough job of ensuring that throughout the destruction process that no modesettings can be done with the connectors. As it is right now, intel_dp_destroy_mst_connector() works like this: * Take all modeset locks * Clear the configuration of the crtc on the connector, if there is one * Drop all modeset locks, this is required because of circular dependency issues that arise with trying to remove the connector from sysfs with modeset locks held * Unregister the connector * Take all modeset locks, again * Do the rest of the required cleaning for destroying the connector * Finally drop all modeset locks for good This only works sometimes. During the destruction process, it's very possible that a userspace application will attempt to do a modesetting using the connector. When we drop the modeset locks, an ioctl handler such as drm_mode_setcrtc has the oppurtunity to take all of the modeset locks from us. When this happens, one thing leads to another and eventually we end up committing a mode with the non-existent connector: [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* failed to enable link training [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7cf0001f [drm:intel_dp_start_link_train [i915]] *ERROR* failed to start channel equalization [drm:intel_dp_aux_ch] dp_aux_ch timeout status 0x7cf0001f [drm:intel_mst_pre_enable_dp [i915]] *ERROR* failed to allocate vcpi And in some cases, such as with the T460s using an MST dock, this results in breaking modesetting and/or panicking the system. To work around this, we now unregister the connector at the very beginning of intel_dp_destroy_mst_connector(), grab all the modesetting locks, and then hold them until we finish the rest of the function. CC: stable@xxxxxxxxxxxxxxx Signed-off-by: Lyude <cpaul@xxxxxxxxxx> Signed-off-by: Rob Clark <rclark@xxxxxxxxxx> Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/1458155884-13877-1-git-send-email-cpaul@xxxxxxxxxx (cherry picked from commit 1f7717552ef1306be3b7ed28c66c6eff550e3a23) Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx> --- drivers/gpu/drm/i915/intel_dp_mst.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c index 463e16d..8266a8d 100644 --- a/drivers/gpu/drm/i915/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/intel_dp_mst.c @@ -452,6 +452,8 @@ static void intel_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr, struct intel_connector *intel_connector = to_intel_connector(connector); struct drm_device *dev = connector->dev; + intel_connector->unregister(intel_connector); + /* need to nuke the connector */ drm_modeset_lock_all(dev); if (connector->state->crtc) { @@ -465,11 +467,7 @@ static void intel_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr, WARN(ret, "Disabling mst crtc failed with %i\n", ret); } - drm_modeset_unlock_all(dev); - intel_connector->unregister(intel_connector); - - drm_modeset_lock_all(dev); intel_connector_remove_from_fbdev(intel_connector); drm_connector_cleanup(connector); drm_modeset_unlock_all(dev); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html