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

[Andy Shevchenko <andy.shevchenko@gmail.com>]

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On Monday, May 3, 2021, Hans de Goede <hdegoede@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@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.


> +}
> +
>
>  /**
>   * 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

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