On Wed, Mar 16, 2016 at 03:18:04PM -0400, Lyude wrote: > 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 So pretty much what I suspected https://lists.freedesktop.org/archives/intel-gfx/2016-February/087734.html > > 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. Are these just kernel oopses etc.? If the hardware gets upset from modesetting when the sink is gone, well, then we still have a problem because the user can of course yank the cable while the modeset is already underway. > > 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> These sobs don't make much sense to me. Patch itself does make sense to me, so Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > --- > 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 fa0dabf..b21ac88 100644 > --- a/drivers/gpu/drm/i915/intel_dp_mst.c > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c > @@ -499,6 +499,8 @@ 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) { > @@ -512,11 +514,7 @@ 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 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
