[Intel-gfx] [PATCH 2/2] drm/doc: Improve docs around connector (un)registration

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Tue, 2019-09-17 at 14:09 +0200, Daniel Vetter wrote:
> Current code is quite a mess unfortunately, so also add a todo.rst
> entry to maybe fix it up eventually.
> 
> Cc: Michel Dänzer <michel at daenzer.net>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  Documentation/gpu/todo.rst      | 12 ++++++++++++
>  drivers/gpu/drm/drm_connector.c | 10 ++++++++--
>  drivers/gpu/drm/drm_dp_helper.c |  8 ++++++++
>  3 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index 32787acff0a8..8dc147c93c9c 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -284,6 +284,18 @@ drm_fb_helper tasks
>    removed: drm_fb_helper_single_add_all_connectors(),
>    drm_fb_helper_add_one_connector() and
> drm_fb_helper_remove_one_connector().
>  
> +connector register/unregister fixes
> +-----------------------------------
> +
> +- For most connectors it's a no-op to call
> drm_connector_register/unregister
> +  directly from driver code, drm_dev_register/unregister take care of this
> +  already. We can remove all of them.
> +
> +- For dp drivers it's a bit more a mess, since we need the connector to be
> +  registered when calling drm_dp_aux_register. Fix this by instead calling
> +  drm_dp_aux_init, and moving the actual registering into a late_register
> +  callback as recommended in the kerneldoc.
> +
>  Core refactorings
>  =================
>  
> diff --git a/drivers/gpu/drm/drm_connector.c
> b/drivers/gpu/drm/drm_connector.c
> index 4c766624b20d..cd5048ceab1d 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -480,7 +480,10 @@ EXPORT_SYMBOL(drm_connector_cleanup);
>   * drm_connector_register - register a connector
>   * @connector: the connector to register
>   *
> - * Register userspace interfaces for a connector
> + * Register userspace interfaces for a connector. Only call this for
> connectors
> + * which can be hotplugged after drm_dev_register() has been called
> already,
> + * e.g. DP MST connectors. All other connectors will be registered
> automatically
> + * when calling drm_dev_register().
>   *
>   * Returns:
>   * Zero on success, error code on failure.
> @@ -526,7 +529,10 @@ EXPORT_SYMBOL(drm_connector_register);
>   * drm_connector_unregister - unregister a connector
>   * @connector: the connector to unregister
>   *
> - * Unregister userspace interfaces for a connector
> + * Unregister userspace interfaces for a connector. Only call this for
> + * connectors which have registered explicitly by calling
> drm_dev_register(),
> + * since connectors are unregistered automatically when
> drm_dev_unregister() is
> + * called.
>   */
>  void drm_connector_unregister(struct drm_connector *connector)
>  {
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
> b/drivers/gpu/drm/drm_dp_helper.c
> index ffc68d305afe..f373798d82f6 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -1109,6 +1109,14 @@ EXPORT_SYMBOL(drm_dp_aux_init);
>   * @aux: DisplayPort AUX channel
>   *
>   * Automatically calls drm_dp_aux_init() if this hasn't been done yet.
> + * This should only be called when the underlying &struct drm_connector is
> + * initialiazed already. Therefore the best place to call this is from
> + * &drm_connector_funcs.late_register. Not that drivers which don't follow
> this
> + * will Oops when CONFIG_DRM_DP_AUX_CHARDEV is enabled.
> + *
> + * Drivers which need to use the aux channel before that point (e.g. at
> driver
> + * load time, before drm_dev_register() has been called) need to call
> + * drm_dp_aux_init().
>   *
>   * Returns 0 on success or a negative error code on failure.
>   */
-- 
Cheers,
	Lyude Paul