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

[Daniel Vetter]

On Tue, Sep 17, 2019 at 03:40:29PM -0400, Lyude Paul wrote:
> Reviewed-by: Lyude Paul <lyude at redhat.com>

Thanks for taking a look, pushed to drm-misc-next.
-Daniel
> 
> 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
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch