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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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1f7717552e
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@vger.kernel.org Signed-off-by: Lyude <cpaul@redhat.com> Signed-off-by: Rob Clark <rclark@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/1458155884-13877-1-git-send-email-cpaul@redhat.com |
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| Makefile | ||