[PATCH 3/9] drm/connector: Add drm_connector_find_by_fwnode() function (v2)

[Hans de Goede]

Hi,

On 5/4/21 10:00 AM, Andy Shevchenko wrote:
> 
> 
> On Monday, May 3, 2021, Hans de Goede <hdegoede at redhat.com <mailto:hdegoede at redhat.com>> wrote:
> 
>     Add a function to find a connector based on a fwnode.
> 
>     This will be used by the new drm_connector_oob_hotplug_event()
>     function which is added by the next patch in this patch-set.
> 
>     Changes in v2:
>     - Complete rewrite to use a global connector list in drm_connector.c
>       rather then using a class-dev-iter in drm_sysfs.c
> 
>     Signed-off-by: Hans de Goede <hdegoede at redhat.com <mailto:hdegoede at redhat.com>>
>     ---
>      drivers/gpu/drm/drm_connector.c     | 50 +++++++++++++++++++++++++++++
>      drivers/gpu/drm/drm_crtc_internal.h |  1 +
>      include/drm/drm_connector.h         |  8 +++++
>      3 files changed, 59 insertions(+)
> 
>     diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
>     index 87c68563e6c3..ef759d6add81 100644
>     --- a/drivers/gpu/drm/drm_connector.c
>     +++ b/drivers/gpu/drm/drm_connector.c
>     @@ -66,6 +66,14 @@
>       * support can instead use e.g. drm_helper_hpd_irq_event().
>       */
> 
>     +/*
>     + * Global connector list for drm_connector_find_by_fwnode().
>     + * Note drm_connector_[un]register() first take connector->lock and then
>     + * take the connector_list_lock.
>     + */
>     +static DEFINE_MUTEX(connector_list_lock);
>     +static LIST_HEAD(connector_list);
>     +
>      struct drm_conn_prop_enum_list {
>             int type;
>             const char *name;
>     @@ -267,6 +275,7 @@ int drm_connector_init(struct drm_device *dev,
>                     goto out_put_type_id;
>             }
> 
>     +       INIT_LIST_HEAD(&connector->global_connector_list_entry);
>             INIT_LIST_HEAD(&connector->probed_modes);
>             INIT_LIST_HEAD(&connector->modes);
>             mutex_init(&connector->mutex);
>     @@ -540,6 +549,9 @@ int drm_connector_register(struct drm_connector *connector)
>                     drm_privacy_screen_register_notifier(connector->privacy_screen,
>                                                &connector->privacy_screen_notifier);
> 
>     +       mutex_lock(&connector_list_lock);
>     +       list_add_tail(&connector->global_connector_list_entry, &connector_list);
>     +       mutex_unlock(&connector_list_lock);
>             goto unlock;
> 
>      err_debugfs:
>     @@ -568,6 +580,10 @@ void drm_connector_unregister(struct drm_connector *connector)
>                     return;
>             }
> 
>     +       mutex_lock(&connector_list_lock);
>     +       list_del_init(&connector->global_connector_list_entry);
>     +       mutex_unlock(&connector_list_lock);
>     +
>             if (connector->privacy_screen)
>                     drm_privacy_screen_unregister_notifier(
>                                             connector->privacy_screen,
>     @@ -2676,6 +2692,40 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>             return ret;
>      }
> 
>     +/**
>     + * drm_connector_find_by_fwnode - Find a connector based on the associated fwnode
>     + * @fwnode: fwnode for which to find the matching drm_connector
>     + *
>     + * This functions looks up a drm_connector based on its associated fwnode. When
>     + * a connector is found a reference to the connector is returned. The caller must
>     + * call drm_connector_put() to release this reference when it is done with the
>     + * connector.
>     + *
>     + * Returns: A reference to the found connector or an ERR_PTR().
>     + */
>     +struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
>     +{
>     +       struct drm_connector *connector, *found = ERR_PTR(-ENODEV);
>     +
>     +       if (!fwnode)
>     +               return ERR_PTR(-ENODEV);
>     +
>     +       mutex_lock(&connector_list_lock);
>     +
>     +       list_for_each_entry(connector, &connector_list, global_connector_list_entry) {
>     +               if (connector->fwnode == fwnode ||
>     +                   (connector->fwnode && connector->fwnode->secondary == fwnode)) {
>     +                       drm_connector_get(connector);
>     +                       found = connector;
>     +                       break;
>     +               }
>     +       }
>     +
>     +       mutex_unlock(&connector_list_lock);
>     +
>     +       return found;
> 
> 
> 
> If I am not mistaken you can replace this with
> 
> return list_entry_is_head();
> 
> call and remove additional Boolean variable.

Found is not a boolean, it is a pointer to the found connector (or ERR_PTR(-ENODEV)).

Regards,

Hans


>  
> 
>     +}
>     +
> 
>      /**
>       * DOC: Tile group
>     diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
>     index 54d4cf1233e9..6e28fc00a740 100644
>     --- a/drivers/gpu/drm/drm_crtc_internal.h
>     +++ b/drivers/gpu/drm/drm_crtc_internal.h
>     @@ -185,6 +185,7 @@ int drm_connector_set_obj_prop(struct drm_mode_object *obj,
>      int drm_connector_create_standard_properties(struct drm_device *dev);
>      const char *drm_get_connector_force_name(enum drm_connector_force force);
>      void drm_connector_free_work_fn(struct work_struct *work);
>     +struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode);
> 
>      /* IOCTL */
>      int drm_connector_property_set_ioctl(struct drm_device *dev,
>     diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
>     index d20bfd7576ed..ae377354e48e 100644
>     --- a/include/drm/drm_connector.h
>     +++ b/include/drm/drm_connector.h
>     @@ -1267,6 +1267,14 @@ struct drm_connector {
>              */
>             struct list_head head;
> 
>     +       /**
>     +        * @global_connector_list_entry:
>     +        *
>     +        * Connector entry in the global connector-list, used by
>     +        * drm_connector_find_by_fwnode().
>     +        */
>     +       struct list_head global_connector_list_entry;
>     +
>             /** @base: base KMS object */
>             struct drm_mode_object base;
>      
>     -- 
>     2.31.1
> 
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>