Re: [Intel-gfx] [PATCH 3/3] drm/atomic: Make private objs proper objects

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Dec 31, 2021 at 03:23:31PM +0200, Jani Nikula wrote:
> On Wed, 12 Jul 2017, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Make the atomic private object stuff less special by introducing proper
> > base classes for the object and its state. Drivers can embed these in
> > their own appropriate objects, after which these things will work
> > exactly like the plane/crtc/connector states during atomic operations.
> >
> > v2: Reorder to not depend on drm_dynarray (Daniel)
> >
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> #v1
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Stumbled upon an old commit
> 
> commit a4370c777406c2810e37fafd166ccddecdb2a60c
> Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Date:   Wed Jul 12 18:51:02 2017 +0300
> 
>     drm/atomic: Make private objs proper objects
> 
> which is this patch.
> 
> > @@ -3050,8 +3043,7 @@ struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_a
> >  	struct drm_device *dev = mgr->dev;
> >  
> >  	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> > -	return drm_atomic_get_private_obj_state(state, mgr,
> > -						&mst_state_funcs);
> > +	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
> >  }
> >  EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
> 
> I don't think this combines well with...
> 
> > diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> > index 177ab6f86855..d55abb75f29a 100644
> > --- a/include/drm/drm_dp_mst_helper.h
> > +++ b/include/drm/drm_dp_mst_helper.h
> > @@ -404,12 +404,17 @@ struct drm_dp_payload {
> >  	int vcpi;
> >  };
> >  
> > +#define to_dp_mst_topology_state(x) container_of(x, struct drm_dp_mst_topology_state, base)
> 
> ...this in case of error pointers that
> drm_atomic_get_private_obj_state() may return.

offsetof(base)==0 so should work in practice.

-- 
Ville Syrjälä
Intel