On Thu, 2019-06-06 at 19:41 +0000, Li, Sun peng (Leo) wrote: > > On 2019-06-03 3:28 p.m., Lyude Paul wrote: > > > I'm reproducing this just by reloading i915 on a machine with some MST > > > displays connected. I uploaded a copy of the script that I use to do > > > this > > > here: > > > > > > https://people.freedesktop.org/~lyudess/archive/06-03-2019/unloadgpumod.sh > > oops-almost forgot to mention. The argument you pass to make it reload > > instead > > of just unloading is --reload > > > > Thanks for the script! > > So, the warning has to do with: > > 1. Having the aux device as a child of connector device, and > 2. During driver unload, drm_connector_unregister() is called before > drm_dp_mst_topology_put_port() > > Which means that connector_unregister() will recursively remove the > child aux device, before put_port() can properly unregister it. Any > further attempts to remove after the first will throw a "not found" warning. > > Call-stacks for reference: > > *drm_connector_unregister*+0x37/0x60 [drm] > drm_connector_unregister_all+0x30/0x60 [drm] > drm_modeset_unregister_all+0xe/0x30 [drm] > drm_dev_unregister+0x9c/0xb0 [drm] > i915_driver_unload+0x73/0x120 [i915] > > drm_dp_aux_unregister_devnode+0xf5/0x180 [drm_kms_helper] > *drm_dp_mst_topology_put_port*+0x4e/0xf0 [drm_kms_helper] > drm_dp_mst_topology_put_mstb+0x91/0x160 [drm_kms_helper] > drm_dp_mst_topology_mgr_set_mst+0x12b/0x2b0 [drm_kms_helper] > ? __finish_swait+0x10/0x40 > drm_dp_mst_topology_mgr_destroy+0x11/0xa0 [drm_kms_helper] > intel_dp_encoder_flush_work+0x32/0xb0 [i915] > intel_ddi_encoder_destroy+0x32/0x60 [i915] > drm_mode_config_cleanup+0x51/0x2e0 [drm] > intel_modeset_cleanup+0xc8/0x140 [i915] > i915_driver_unload+0xa0/0x120 [i915] > > A solution is to unregister the aux device immediately before the > connector device is unregistered - if we are to keep the aux device as a > child. Following current scheme with SST, it looks like > drm_connector_funcs->early_unregister() is the right place to do so. > To keep the balance, aux registration will then happen in > drm_connector_funcs->late_register(). This will leave the SDP > transaction handling part in DRM still, but pass the responsibility of > creating and removing remote (fake) aux devices to the driver. > > I have a WIP patch here for you to take a look. It should apply on top > of the existing patchset: > https://pastebin.com/1YJZhL4C > This approach seems fine to me! I was thinking we might end up doing something like this. My only thought is that we can probably write up a drm_dp_mst_connector_late_register() and drm_dp_mst_connector_early_unregister() that drivers can call from their →late_register()/→early_unregister() callbacks that handles printing the debug message, setting the parent and registering/unregistering the aux device. I'd imagine someday in the future we'll probably have more things to add to those callbacks for mst as well. > I'd like to hear your thoughts, before I go and modify other drivers :) > > Thanks, > Leo -- Cheers, Lyude Paul _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
