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

[Dmitry Baryshkov]

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?

>  
>  /**
> @@ -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