[PATCH 02/28] drm/writeback: Add a helper function to get writeback connector

[Kandpal, Suraj]

> -----Original Message-----
> From: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
> Sent: Saturday, July 26, 2025 5:50 PM
> To: Kandpal, Suraj <suraj.kandpal at intel.com>
> Cc: dri-devel at lists.freedesktop.org; intel-xe at lists.freedesktop.org; intel-
> gfx at lists.freedesktop.org; Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>;
> Murthy, Arun R <arun.r.murthy at intel.com>; Shankar, Uma
> <uma.shankar at intel.com>
> Subject: Re: [PATCH 02/28] drm/writeback: Add a helper function to get
> writeback connector
> 
> On Fri, Jul 25, 2025 at 10:33:43AM +0530, Suraj Kandpal wrote:
> > Now that we can initialize a drm_writeback_connector without having to
> > initialize the drm_connector within it and leaving the responsibility
> > of initialising the drm_connector and maintaining the association with
> > drm_writeback_connector to it. This helper hooks lets drivers return
> > the drm_writeback_connector associated with the give drm_connector.
> >
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >  drivers/gpu/drm/drm_writeback.c          | 14 ++++++
> >  include/drm/drm_modeset_helper_vtables.h | 59
> ++++++++++++++++++++++++
> >  include/drm/drm_writeback.h              | 14 ++++--
> >  3 files changed, 82 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_writeback.c
> > b/drivers/gpu/drm/drm_writeback.c index fa58eb0dc7bf..e9f7123270d6
> > 100644
> > --- a/drivers/gpu/drm/drm_writeback.c
> > +++ b/drivers/gpu/drm/drm_writeback.c
> > @@ -107,6 +107,19 @@ static const struct dma_fence_ops
> drm_writeback_fence_ops = {
> >  	.get_timeline_name = drm_writeback_fence_get_timeline_name,
> >  };
> >
> > +struct drm_writeback_connector *
> > +drm_connector_to_writeback(struct drm_connector *connector) {
> > +	const struct drm_connector_helper_funcs *funcs =
> > +		connector->helper_private;
> > +
> > +	if (funcs->get_writeback_connector)
> > +		return funcs->get_writeback_connector(connector);
> > +
> > +	return container_of(connector, struct drm_writeback_connector,
> > +base); } EXPORT_SYMBOL(drm_connector_to_writeback);
> > +
> >  static int create_writeback_properties(struct drm_device *dev)  {
> >  	struct drm_property *prop;
> > @@ -443,6 +456,7 @@ drm_writeback_connector_init_with_conn(struct
> drm_device *dev, struct drm_connec
> >  				       struct drm_writeback_connector
> *wb_connector,
> >  				       struct drm_encoder *enc,
> >  				       const struct drm_connector_funcs
> *con_funcs,
> > +				       const struct
> drm_writeback_connector_helper_funcs
> > +*wb_funcs,
> >  				       const u32 *formats, int n_formats)  {
> >  	struct drm_property_blob *blob;
> > diff --git a/include/drm/drm_modeset_helper_vtables.h
> > b/include/drm/drm_modeset_helper_vtables.h
> > index ce7c7aeac887..6b89b33d2304 100644
> > --- a/include/drm/drm_modeset_helper_vtables.h
> > +++ b/include/drm/drm_modeset_helper_vtables.h
> > @@ -31,6 +31,7 @@
> >
> >  #include <drm/drm_crtc.h>
> >  #include <drm/drm_encoder.h>
> > +#include <drm/drm_writeback.h>
> >
> >  /**
> >   * DOC: overview
> > @@ -1179,6 +1180,25 @@ struct drm_connector_helper_funcs {
> >  	 *
> >  	 */
> >  	void (*disable_hpd)(struct drm_connector *connector);
> > +
> > +	/**
> > +	 * @get_writeback_connector:
> > +	 *
> > +	 * This callback is used by drivers to get the writeback connector in
> > +	 * case the init is done via drm_writeback_init_with_conn. Which
> means
> > +	 * the drivers don't have drm_connector embedded in
> drm_writeback_connector
> > +	 * so they need to send the associated writeback connector with this
> > +	 * function.
> > +	 *
> > +	 * This operation is optional.
> > +	 *
> > +	 * This is mainly called from drm_writeback_set_gb.
> > +	 *
> > +	 * RETURNS:
> > +	 *
> > +	 * drm_writeback_connector assoiciated with the drm connector.
> > +	 */
> > +	struct drm_writeback_connector *(*get_writeback_connector)(struct
> > +drm_connector *connector);
> >  };
> >
> >  /**
> > @@ -1192,6 +1212,45 @@ static inline void
> drm_connector_helper_add(struct drm_connector *connector,
> >  	connector->helper_private = funcs;
> >  }
> >
> > +/**
> > + * struct drm_writeback_connector_helper_funcs - helper operations
> > +for writeback
> > + * connectors.
> > + *
> > + * These functions are used by the atomic and legacy modeset helpers
> > +and by the
> > + * probe helpers.
> > + */
> > +struct drm_writeback_connector_helper_funcs {
> > +	/**
> > +	 * @get_connector_from_writeback:
> > +	 *
> > +	 * This callback is used by drivers to get the drm_connector in
> > +	 * case the init is done via drm_writeback_init_with_conn. Which
> means
> > +	 * the drivers don't have drm_connector embedded in
> drm_writeback_connector
> > +	 * so they need to send the associated drm_connector with this
> > +	 * function.
> > +	 *
> > +	 * This operation is optional.
> > +	 *
> > +	 * RETURNS:
> > +	 *
> > +	 * drm_connector assoiciated with the drm_writeback_connector.
> > +	 */
> > +	struct drm_connector
> > +	*(*get_connector_from_writeback)(struct drm_writeback_connector
> > +*wbconnector); };
> > +
> > +/**
> > + * drm_writeback_connector_helper_add - sets the helper vtable for a
> > +connector
> > + * @wb_connector: DRM writeback connector
> > + * @funcs: helper vtable to set for @wb_connector  */ static inline
> > +void drm_writeback_connector_helper_add(struct
> > +drm_writeback_connector *wb_connector,
> > +				   const struct
> drm_writeback_connector_helper_funcs *funcs) {
> > +	wb_connector->helper_private = funcs; }
> > +
> >  /**
> >   * struct drm_plane_helper_funcs - helper operations for planes
> >   *
> > diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
> > index 149744dbeef0..77c3c64c132d 100644
> > --- a/include/drm/drm_writeback.h
> > +++ b/include/drm/drm_writeback.h
> > @@ -84,6 +84,13 @@ struct drm_writeback_connector {
> >  	 * The name of the connector's fence timeline.
> >  	 */
> >  	char timeline_name[32];
> > +
> > +	/**
> > +	 * @helper_private:
> > +	 *
> > +	 * helper private funcs for writeback_connector
> > +	 */
> > +	const struct drm_writeback_connector_helper_funcs
> *helper_private;
> >  };
> 
> Unrelate to the commit? Also, where is this defined?

This is very much related to this commit and defined on top right here in this commit.

Regards,
Suraj Kandpal

> 
> >
> >  /**
> > @@ -142,11 +149,7 @@ struct drm_writeback_job {
> >  	void *priv;
> >  };
> >
> > -static inline struct drm_writeback_connector *
> > -drm_connector_to_writeback(struct drm_connector *connector) -{
> > -	return container_of(connector, struct drm_writeback_connector,
> base);
> > -}
> > +struct drm_writeback_connector *drm_connector_to_writeback(struct
> > +drm_connector *connector);
> >
> >  int drm_writeback_connector_init(struct drm_device *dev,
> >  				 struct drm_writeback_connector
> *wb_connector, @@ -172,6 +175,7
> > @@ drm_writeback_connector_init_with_conn(struct drm_device *dev,
> struct drm_connec
> >  				       struct drm_writeback_connector
> *wb_connector,
> >  				       struct drm_encoder *enc,
> >  				       const struct drm_connector_funcs
> *con_funcs,
> > +				       const struct
> drm_writeback_connector_helper_funcs
> > +*wb_funcs,
> >  				       const u32 *formats, int n_formats);
> >
> >  int drm_writeback_set_fb(struct drm_connector_state *conn_state,
> > --
> > 2.34.1
> >
> 
> --
> With best wishes
> Dmitry