On Mon, Dec 02, 2024 at 10:07:23PM +0200, Imre Deak wrote: > On Mon, Dec 02, 2024 at 05:35:34PM +0100, Simona Vetter wrote: > > On Tue, Nov 26, 2024 at 06:18:56PM +0200, Imre Deak wrote: > > > Atm when the connector is added to the drm_mode_config::connector_list, > > > the connector may not be fully initialized yet. This is not a problem > > > for user space, which will see the connector only after it's registered > > > later, it could be a problem for in-kernel users looking up connectors > > > via the above list. > > > > > > To resolve the above issue, add a way to separately initialize the DRM > > > core specific parts of the connector and add it to the above list. This > > > will move adding the connector to the list after the properties on the > > > connector have been added, this is ok since these steps don't have a > > > dependency. > > > > > > v2: (Jani) > > > - Let initing DDC as well via drm_connector_init_core(). > > > - Rename __drm_connector_init to drm_connector_init_core_and_add(). > > > > > > Cc: Jani Nikula <jani.nikula@xxxxxxxxx> > > > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> (v1) > > > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > > > > So looking at the thread, I guess it'd be good to document some consensus > > stance on kunit tests, and whether or not we're at the point where for new > > things or extensions of functions that already have kunit coverage we need > > them. But I think that's orthogonal. > > > > On the patch itself, I don't think it's the right fix. And by extension, I > > don't think the i915 fix is correct either, because we have a bigger mess > > here: > > > > - GETCONNECTOR does indeed not show a connector that's not yet registers. > > > > - But GETRESOURCES happily lists them. Which means we have a very silly > > race here, which isn't good. > > Right, didn't notice that, it needs to be fixed as well. > > > - I think the correct solution is to move the list_add to the registration > > step, which would also move connectors in-line with other dynamically > > added kms objects like blobs or fbs (although those have a single-step > > registration+init function, so it's less obvious what's going on). > > > > - The same thing applies on the unregister side of things, once a > > connector is unregistered I don't think it should stick around in any > > list. But I'm not entirely sure, would need to check with Lyude to make > > sure this doesn't break anything in mst helpers. > > > > Now implementing this is going to be a bit a mess: > > > > - For static connectors drivers _really_ want the connectors to be on the > > lists, otherwise a lot of the driver setup code just wont work. And > > we've worked towards removing all the explicit drm_connector_register > > calls, readding feels a bit silly. > > > > - I think short-term we could just use the connector type to decide this, > > if it's MST it's a dynamic connector, and the list_add would need to be > > done late in drm_connector_register. > > > > - Once the need pops up for other connectors to be dynamic (like for > > dynamic drm_bridge hotplug) we can add a drm_connector_dynamic_init or > > similar. I don't think splitting up _init further like you do here in > > two functions is correct, because the only place where it's correct to > > add a dynamic/hotplugged connector to the lists is in > > drm_connector_register, not anywhere else. > > Afaiu the above means adding drm_connector_dynamic_init() which would > only init the connector w/o adding it to the connector list (i.e. what > drm_connector_init_core() does) and adding this connector to the list > from drm_connector_register(), hence not needing the drm_connector_add() > interface. drm_connector_dynamic_init() is the more explicit approach, my suggestion was to just hard-code this behavior for dp mst connectors. Which is a bit a hack. Either is fine with me. > I agree this would be better, in the following way: the deferred > registration via drm_connector_register_all() should continue to work - > if drm_connector_register() is called by the driver before the drm > device is registered. So a dynamically inited connector should be added > to the list - if not yet added - early in the function before returning > if the drm device is not yet registered. > > Are you ok with the above for now, also fixing GETRESOURCES by checking > there if the connector is already registered? I don't think you need to check for registered connectors. For dynamic ones this should be impossible, and userspace cannot call any ioctl before drm_dev_register registers all the non-dynamic connectors. > Moving the addition of the connector to the list later could be done > once the deferred registration happens in a different way (i.e. not via > the current connector list). I don't think you need that special case, the current code should work, even for dynamic connectors? Cheers, Sima > > > - It would be really nice if we could add a check to > > drm_connector_register to make sure it's not called for any connector > > which is already on the connector list, since that's a driver bug. Of > > course this would mean we'd need to split that from the internal version > > we call from drm_dev_register. > > > > Unfortunately that's not yet doable because the following todo isn't > > completed yet: > > > > https://dri.freedesktop.org/docs/drm/gpu/todo.html#connector-register-unregister-fixes > > > > I guess just add another bullet there? > > > > Does this sound like a plan or am I completely wrong here? > > > > Cheers, Sima > > > > > > > --- > > > drivers/gpu/drm/drm_connector.c | 111 ++++++++++++++++++++++++++------ > > > include/drm/drm_connector.h | 6 ++ > > > 2 files changed, 97 insertions(+), 20 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > > > index fc35f47e2849e..fd7acae8656b2 100644 > > > --- a/drivers/gpu/drm/drm_connector.c > > > +++ b/drivers/gpu/drm/drm_connector.c > > > @@ -218,11 +218,11 @@ void drm_connector_free_work_fn(struct work_struct *work) > > > } > > > } > > > > > > -static int __drm_connector_init(struct drm_device *dev, > > > - struct drm_connector *connector, > > > - const struct drm_connector_funcs *funcs, > > > - int connector_type, > > > - struct i2c_adapter *ddc) > > > +static int __drm_connector_init_core(struct drm_device *dev, > > > + struct drm_connector *connector, > > > + const struct drm_connector_funcs *funcs, > > > + int connector_type, > > > + struct i2c_adapter *ddc) > > > { > > > struct drm_mode_config *config = &dev->mode_config; > > > int ret; > > > @@ -273,6 +273,7 @@ static int __drm_connector_init(struct drm_device *dev, > > > /* provide ddc symlink in sysfs */ > > > connector->ddc = ddc; > > > > > > + INIT_LIST_HEAD(&connector->head); > > > INIT_LIST_HEAD(&connector->global_connector_list_entry); > > > INIT_LIST_HEAD(&connector->probed_modes); > > > INIT_LIST_HEAD(&connector->modes); > > > @@ -288,14 +289,6 @@ static int __drm_connector_init(struct drm_device *dev, > > > > > > drm_connector_get_cmdline_mode(connector); > > > > > > - /* We should add connectors at the end to avoid upsetting the connector > > > - * index too much. > > > - */ > > > - spin_lock_irq(&config->connector_list_lock); > > > - list_add_tail(&connector->head, &config->connector_list); > > > - config->num_connector++; > > > - spin_unlock_irq(&config->connector_list_lock); > > > - > > > if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL && > > > connector_type != DRM_MODE_CONNECTOR_WRITEBACK) > > > drm_connector_attach_edid_property(connector); > > > @@ -332,6 +325,86 @@ static int __drm_connector_init(struct drm_device *dev, > > > return ret; > > > } > > > > > > +/** > > > + * drm_connector_init_core - Initialize the core state of a preallocated connector > > > + * @dev: DRM device > > > + * @connector: the connector to init > > > + * @funcs: callbacks for this connector > > > + * @connector_type: user visible type of the connector > > > + * @ddc: pointer to the associated ddc adapter > > > + * > > > + * Initialises the core state of preallocated connector. This is > > > + * equivalent to drm_connector_init(), without adding the connector to > > > + * drm_mode_config::connector_list. This call must be followed by calling > > > + * drm_connector_add() during initialization to expose the connector to > > > + * in-kernel users via the above list. > > > + * > > > + * Returns: > > > + * Zero on success, error code on failure. > > > + */ > > > +int drm_connector_init_core(struct drm_device *dev, > > > + struct drm_connector *connector, > > > + const struct drm_connector_funcs *funcs, > > > + int connector_type, > > > + struct i2c_adapter *ddc) > > > +{ > > > + if (drm_WARN_ON(dev, !(funcs && funcs->destroy))) > > > + return -EINVAL; > > > + > > > + return __drm_connector_init_core(dev, connector, funcs, connector_type, ddc); > > > +} > > > +EXPORT_SYMBOL(drm_connector_init_core); > > > + > > > +/** > > > + * drm_connector_add - Add the connector > > > + * @connector: the connector to add > > > + * > > > + * Add the connector to the drm_mode_config::connector_list, exposing the > > > + * connector to in-kernel users. This call must be preceded by a call to > > > + * drm_connector_init_core(). > > > + */ > > > +void drm_connector_add(struct drm_connector *connector) > > > +{ > > > + struct drm_device *dev = connector->dev; > > > + struct drm_mode_config *config = &dev->mode_config; > > > + > > > + spin_lock_irq(&config->connector_list_lock); > > > + list_add_tail(&connector->head, &config->connector_list); > > > + config->num_connector++; > > > + spin_unlock_irq(&config->connector_list_lock); > > > +} > > > +EXPORT_SYMBOL(drm_connector_add); > > > + > > > +static void drm_connector_remove(struct drm_connector *connector) > > > +{ > > > + struct drm_device *dev = connector->dev; > > > + > > > + if (list_empty(&connector->head)) > > > + return; > > > + > > > + spin_lock_irq(&dev->mode_config.connector_list_lock); > > > + list_del_init(&connector->head); > > > + dev->mode_config.num_connector--; > > > + spin_unlock_irq(&dev->mode_config.connector_list_lock); > > > +} > > > + > > > +static int drm_connector_init_core_and_add(struct drm_device *dev, > > > + struct drm_connector *connector, > > > + const struct drm_connector_funcs *funcs, > > > + int connector_type, > > > + struct i2c_adapter *ddc) > > > +{ > > > + int ret; > > > + > > > + ret = __drm_connector_init_core(dev, connector, funcs, connector_type, ddc); > > > + if (ret) > > > + return ret; > > > + > > > + drm_connector_add(connector); > > > + > > > + return 0; > > > +} > > > + > > > /** > > > * drm_connector_init - Init a preallocated connector > > > * @dev: DRM device > > > @@ -361,7 +434,7 @@ int drm_connector_init(struct drm_device *dev, > > > if (drm_WARN_ON(dev, !(funcs && funcs->destroy))) > > > return -EINVAL; > > > > > > - return __drm_connector_init(dev, connector, funcs, connector_type, NULL); > > > + return drm_connector_init_core_and_add(dev, connector, funcs, connector_type, NULL); > > > } > > > EXPORT_SYMBOL(drm_connector_init); > > > > > > @@ -398,7 +471,7 @@ int drm_connector_init_with_ddc(struct drm_device *dev, > > > if (drm_WARN_ON(dev, !(funcs && funcs->destroy))) > > > return -EINVAL; > > > > > > - return __drm_connector_init(dev, connector, funcs, connector_type, ddc); > > > + return drm_connector_init_core_and_add(dev, connector, funcs, connector_type, ddc); > > > } > > > EXPORT_SYMBOL(drm_connector_init_with_ddc); > > > > > > @@ -442,7 +515,7 @@ int drmm_connector_init(struct drm_device *dev, > > > if (drm_WARN_ON(dev, funcs && funcs->destroy)) > > > return -EINVAL; > > > > > > - ret = __drm_connector_init(dev, connector, funcs, connector_type, ddc); > > > + ret = drm_connector_init_core_and_add(dev, connector, funcs, connector_type, ddc); > > > if (ret) > > > return ret; > > > > > > @@ -659,10 +732,8 @@ void drm_connector_cleanup(struct drm_connector *connector) > > > connector->name = NULL; > > > fwnode_handle_put(connector->fwnode); > > > connector->fwnode = NULL; > > > - spin_lock_irq(&dev->mode_config.connector_list_lock); > > > - list_del(&connector->head); > > > - dev->mode_config.num_connector--; > > > - spin_unlock_irq(&dev->mode_config.connector_list_lock); > > > + > > > + drm_connector_remove(connector); > > > > > > WARN_ON(connector->state && !connector->funcs->atomic_destroy_state); > > > if (connector->state && connector->funcs->atomic_destroy_state) > > > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h > > > index e3fa43291f449..2476dcbd3c34d 100644 > > > --- a/include/drm/drm_connector.h > > > +++ b/include/drm/drm_connector.h > > > @@ -2122,6 +2122,12 @@ struct drm_connector { > > > > > > #define obj_to_connector(x) container_of(x, struct drm_connector, base) > > > > > > +int drm_connector_init_core(struct drm_device *dev, > > > + struct drm_connector *connector, > > > + const struct drm_connector_funcs *funcs, > > > + int connector_type, > > > + struct i2c_adapter *ddc); > > > +void drm_connector_add(struct drm_connector *connector); > > > int drm_connector_init(struct drm_device *dev, > > > struct drm_connector *connector, > > > const struct drm_connector_funcs *funcs, > > > -- > > > 2.44.2 > > > > > > > -- > > Simona Vetter > > Software Engineer, Intel Corporation > > http://blog.ffwll.ch -- Simona Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
