[PATCH v3 01/39] drm/bridge: add ->edid_read hook and drm_bridge_edid_read()

[Neil Armstrong]

On 23/01/2024 20:37, Jani Nikula wrote:
> Add new struct drm_edid based ->edid_read hook and
> drm_bridge_edid_read() function to call the hook.
> 
> v2: Include drm/drm_edid.h
> 
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>   drivers/gpu/drm/drm_bridge.c | 46 +++++++++++++++++++++++++++++++++++-
>   include/drm/drm_bridge.h     | 33 ++++++++++++++++++++++++++
>   2 files changed, 78 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index cee3188adf3d..4f6f8c662d3f 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -27,8 +27,9 @@
>   #include <linux/mutex.h>
>   
>   #include <drm/drm_atomic_state_helper.h>
> -#include <drm/drm_debugfs.h>
>   #include <drm/drm_bridge.h>
> +#include <drm/drm_debugfs.h>
> +#include <drm/drm_edid.h>
>   #include <drm/drm_encoder.h>
>   #include <drm/drm_file.h>
>   #include <drm/drm_of.h>
> @@ -1206,6 +1207,47 @@ int drm_bridge_get_modes(struct drm_bridge *bridge,
>   }
>   EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
>   
> +/**
> + * drm_bridge_edid_read - read the EDID data of the connected display
> + * @bridge: bridge control structure
> + * @connector: the connector to read EDID for
> + *
> + * If the bridge supports output EDID retrieval, as reported by the
> + * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.edid_read to get
> + * the EDID and return it. Otherwise return NULL.
> + *
> + * If &drm_bridge_funcs.edid_read is not set, fall back to using
> + * drm_bridge_get_edid() and wrapping it in struct drm_edid.
> + *
> + * RETURNS:
> + * The retrieved EDID on success, or NULL otherwise.
> + */
> +const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,
> +					    struct drm_connector *connector)
> +{
> +	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
> +		return NULL;
> +
> +	/* Transitional: Fall back to ->get_edid. */
> +	if (!bridge->funcs->edid_read) {
> +		const struct drm_edid *drm_edid;
> +		struct edid *edid;
> +
> +		edid = drm_bridge_get_edid(bridge, connector);
> +		if (!edid)
> +			return NULL;
> +
> +		drm_edid = drm_edid_alloc(edid, (edid->extensions + 1) * EDID_LENGTH);
> +
> +		kfree(edid);
> +
> +		return drm_edid;
> +	}
> +
> +	return bridge->funcs->edid_read(bridge, connector);
> +}
> +EXPORT_SYMBOL_GPL(drm_bridge_edid_read);
> +
>   /**
>    * drm_bridge_get_edid - get the EDID data of the connected display
>    * @bridge: bridge control structure
> @@ -1215,6 +1257,8 @@ EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
>    * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
>    * get the EDID and return it. Otherwise return NULL.
>    *
> + * Deprecated. Prefer using drm_bridge_edid_read().
> + *
>    * RETURNS:
>    * The retrieved EDID on success, or NULL otherwise.
>    */
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index e39da5807ba7..b7aed3ead705 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -557,6 +557,37 @@ struct drm_bridge_funcs {
>   	int (*get_modes)(struct drm_bridge *bridge,
>   			 struct drm_connector *connector);
>   
> +	/**
> +	 * @edid_read:
> +	 *
> +	 * Read the EDID data of the connected display.
> +	 *
> +	 * The @edid_read callback is the preferred way of reporting mode
> +	 * information for a display connected to the bridge output. Bridges
> +	 * that support reading EDID shall implement this callback and leave
> +	 * the @get_modes callback unimplemented.
> +	 *
> +	 * The caller of this operation shall first verify the output
> +	 * connection status and refrain from reading EDID from a disconnected
> +	 * output.
> +	 *
> +	 * This callback is optional. Bridges that implement it shall set the
> +	 * DRM_BRIDGE_OP_EDID flag in their &drm_bridge->ops.
> +	 *
> +	 * The connector parameter shall be used for the sole purpose of EDID
> +	 * retrieval, and shall not be stored internally by bridge drivers for
> +	 * future usage.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * An edid structure newly allocated with drm_edid_alloc() or returned
> +	 * from drm_edid_read() family of functions on success, or NULL
> +	 * otherwise. The caller is responsible for freeing the returned edid
> +	 * structure with drm_edid_free().
> +	 */
> +	const struct drm_edid *(*edid_read)(struct drm_bridge *bridge,
> +					    struct drm_connector *connector);
> +
>   	/**
>   	 * @get_edid:
>   	 *
> @@ -888,6 +919,8 @@ drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge,
>   enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge);
>   int drm_bridge_get_modes(struct drm_bridge *bridge,
>   			 struct drm_connector *connector);
> +const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,
> +					    struct drm_connector *connector);
>   struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
>   				 struct drm_connector *connector);
>   void drm_bridge_hpd_enable(struct drm_bridge *bridge,

Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>