From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0523EE7717F for ; Thu, 12 Dec 2024 10:04:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EB2F710ED22; Thu, 12 Dec 2024 10:04:25 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="lo6nsPMJ"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4771210ED19; Thu, 12 Dec 2024 10:04:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733997864; x=1765533864; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=aaNMOw6yGg2hcR4hcdf8fbQZuFptfqmNNZxlpj9bgFU=; b=lo6nsPMJVVpAtMDeAuVvbMVCYZXi1QrSDnTXWuEyF7Vw8H0vD6X67Lig s13U18Z4fA7NlnrYeBwoevuK5SEqYod1AOSchBzppHmE0VqZF3em/rga5 Du+1pBhzPTQMLgoVON24wNO6KeKfn7CFuPf8aFNkKDcP2Hak8kwyIC3yh DfMF4CzIHwUD6b8mIHCrjRPNczpFhnKchjVetxy/ZmOfqtui0QQUcYpaj que5AGbcYWNaJK3t0KvYdiP7uTAgt2jeFLGxNeLlkiq+EAM8YELRD/WI7 lkferjiTRnhYOHNQxQtXjK/d2Hjh+LNujrlitEir6JN8dnFHtoZRPS5LT Q==; X-CSE-ConnectionGUID: B7SdyMZZTHe3Xw1VZ0uXNQ== X-CSE-MsgGUID: NJ94ktS1Qz2CxEAc6ERG9A== X-IronPort-AV: E=McAfee;i="6700,10204,11283"; a="45016870" X-IronPort-AV: E=Sophos;i="6.12,228,1728975600"; d="scan'208";a="45016870" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2024 02:04:23 -0800 X-CSE-ConnectionGUID: CCF6+7yQTw6w3QdGgsxrzA== X-CSE-MsgGUID: mYZQINX/S1iqZDGm4rrFLw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="133571320" Received: from klitkey1-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.246.101]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2024 02:04:21 -0800 From: Jani Nikula To: Imre Deak , intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Simona Vetter , Maxime Ripard , Rodrigo Vivi Subject: Re: [PATCH v3 01/11] drm/connector: Add a way to init/add a connector in separate steps In-Reply-To: <20241211230328.4012496-2-imre.deak@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20241211230328.4012496-1-imre.deak@intel.com> <20241211230328.4012496-2-imre.deak@intel.com> Date: Thu, 12 Dec 2024 12:04:17 +0200 Message-ID: <87jzc5xlni.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, 12 Dec 2024, 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 static connectors initialized/added during driver loading, for which > the driver ensures that look-ups via the above list are not possible > until all the connector and other required state is fully initialized > already. It's also not a problem for user space looking up either a > static or dynamic (see what this is below) connector, since this will be > only possible once the connector is registered. > > A dynamic - atm only a DP MST - connector can be initialized and added > after the load time initialization is done. Such a connector may be > looked up by in-kernel users once it's added to the connector list. In > particular a hotplug handler could perform a detection on all the > connectors on the list and hence find a connector there which isn't yet > initialized. For instance the connector's helper hooks may be unset, > leading to a NULL dereference while the detect helper calls the > connector's drm_connector_helper_funcs::detect() or detect_ctx() > handler. > > To resolve the above issue, add a way for dynamic connectors to > separately initialize the DRM core specific parts of the connector > without adding it to the connector list - by calling the new > drm_connector_dynamic_init() - and to add the connector to the list > later once all the initialization is complete and the connector is > registered - by calling the new drm_connector_dynamic_register(). > > Adding the above 2 functions was also motivated to make the distinction > of the interface between static and dynamic connectors clearer: Drivers > should manually initialize and register only dynamic connectors (with > the above 2 functions). A driver should only initialize a static > connector (with one of the drm_connector_init*, drmm_connector_init* > functions) while the registration of the connector will be done > automatically by DRM core. > > v2: (Jani) > - Let initing DDC as well via drm_connector_init_core(). > - Rename __drm_connector_init to drm_connector_init_core_and_add(). > > v3: > - Rename drm_connector_init_core() to drm_connector_dynamic_init(). > (Sima) > - Instead of exporting drm_connector_add(), move adding the connector > to the registration step via a new drm_connector_dynamic_register(). > (Sima) > - Update drm_connector_dynamic_init()'s function documentation and the > commit log according to the above changes. > - Update the commit log describing the problematic scenario during > connector detection. (Maxime) > > Cc: Jani Nikula > Cc: Simona Vetter > Cc: Maxime Ripard > Reviewed-by: Rodrigo Vivi (v1) > Signed-off-by: Imre Deak Overall Reviewed-by: Jani Nikula with some non-blocking subjective nitpicks inline. > --- > drivers/gpu/drm/drm_connector.c | 150 +++++++++++++++++++++++++++----- > include/drm/drm_connector.h | 6 ++ > 2 files changed, 136 insertions(+), 20 deletions(-) > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index fc35f47e2849e..a53e5629ba6c1 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_only(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); Side note, it's confusing the node is called a head, and its documentation actually describes it as a "list of all connectors". > 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 +325,58 @@ static int __drm_connector_init(struct drm_device *dev, > return ret; > } > > +static void drm_connector_add(struct drm_connector *connector) > +{ > + struct drm_device *dev = connector->dev; > + struct drm_mode_config *config = &dev->mode_config; > + > + /* > + * TODO: Change this to a WARN, once all drivers are converted to > + * call drm_connector_dynamic_init() for MST connectors. > + */ > + if (!list_empty(&connector->head)) > + return; > + > + 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); > +} > + > +static void drm_connector_remove(struct drm_connector *connector) > +{ > + struct drm_device *dev = connector->dev; > + > + /* > + * For dynamic connectors drm_connector_cleanup() can call this function > + * before the connector is registered and added to the list. > + */ > + 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); > +} I think there's a bit much going on in this patch, and the splitting of the above functions could've been a separate prep patch. > + > +static int drm_connector_init_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_only(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 > @@ -361,10 +406,51 @@ 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_and_add(dev, connector, funcs, connector_type, NULL); > } > EXPORT_SYMBOL(drm_connector_init); > > +/** > + * drm_connector_dynamic_init - Init a preallocated dynamic 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 a preallocated dynamic connector. Connectors should be > + * subclassed as part of driver connector objects. The connector > + * structure should not be allocated with devm_kzalloc(). > + * > + * Drivers should call this for dynamic connectors which can be hotplugged > + * after drm_dev_register() has been called already, e.g. DP MST connectors. > + * For all other - static - connectors, drivers should call one of the > + * drm_connector_init*()/drmm_connector_init*() functions. > + * > + * After calling this function the drivers must call > + * drm_connector_dynamic_register(). > + * > + * To remove the connector the driver must call drm_connector_unregister() > + * followed by drm_connector_put(). Putting the last reference will call the > + * driver's &drm_connector_funcs.destroy hook, which in turn must call > + * drm_connector_cleanup() and free the connector structure. > + * > + * Returns: > + * Zero on success, error code on failure. > + */ > +int drm_connector_dynamic_init(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_only(dev, connector, funcs, connector_type, ddc); > +} > +EXPORT_SYMBOL(drm_connector_dynamic_init); > + > /** > * drm_connector_init_with_ddc - Init a preallocated connector > * @dev: DRM device > @@ -398,7 +484,7 @@ 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_and_add(dev, connector, funcs, connector_type, ddc); > } > EXPORT_SYMBOL(drm_connector_init_with_ddc); > > @@ -442,7 +528,7 @@ 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_and_add(dev, connector, funcs, connector_type, ddc); > if (ret) > return ret; > > @@ -659,10 +745,8 @@ 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) > @@ -749,6 +833,32 @@ int drm_connector_register(struct drm_connector *connector) > } > EXPORT_SYMBOL(drm_connector_register); > > +/** > + * drm_connector_dynamic_register - register a dynamic connector > + * @connector: the connector to register > + * > + * Register userspace interfaces for a connector. Only call this for connectors > + * initialized by calling drm_connector_dynamic_init(). All other connectors > + * will be registered automatically when calling drm_dev_register(). > + * > + * When the connector is no longer available the driver must call > + * drm_connector_unregister(). > + * > + * Returns: > + * Zero on success, error code on failure. > + */ > +int drm_connector_dynamic_register(struct drm_connector *connector) > +{ > + /* Was the connector inited already? */ > + if (WARN_ON(!(connector->funcs && connector->funcs->destroy))) > + return -EINVAL; > + > + drm_connector_add(connector); > + > + return drm_connector_register(connector); > +} > +EXPORT_SYMBOL(drm_connector_dynamic_register); On the one hand I don't want to rehash this series anymore, but on the other hand... if the dynamic register set a flag, say connector->dynamic or whatever, we could keep the single drm_connector_register() that behaves slightly differently for dynamically initialized connectors. And it could provide some extra sanity checking as well. But *shrug*. This works. BR, Jani. > + > /** > * drm_connector_unregister - unregister a connector > * @connector: the connector to unregister > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h > index e3fa43291f449..f766d194221d1 100644 > --- a/include/drm/drm_connector.h > +++ b/include/drm/drm_connector.h > @@ -2126,6 +2126,11 @@ int drm_connector_init(struct drm_device *dev, > struct drm_connector *connector, > const struct drm_connector_funcs *funcs, > int connector_type); > +int drm_connector_dynamic_init(struct drm_device *dev, > + struct drm_connector *connector, > + const struct drm_connector_funcs *funcs, > + int connector_type, > + struct i2c_adapter *ddc); > int drm_connector_init_with_ddc(struct drm_device *dev, > struct drm_connector *connector, > const struct drm_connector_funcs *funcs, > @@ -2147,6 +2152,7 @@ int drmm_connector_hdmi_init(struct drm_device *dev, > unsigned int max_bpc); > void drm_connector_attach_edid_property(struct drm_connector *connector); > int drm_connector_register(struct drm_connector *connector); > +int drm_connector_dynamic_register(struct drm_connector *connector); > void drm_connector_unregister(struct drm_connector *connector); > int drm_connector_attach_encoder(struct drm_connector *connector, > struct drm_encoder *encoder); -- Jani Nikula, Intel