[PATCH v1 4/6] drm: writeback: document callbacks

[Sam Ravnborg]

Document the callbacks:
    drm_connector_helper_funcs.prepare_writeback_job
    drm_connector_helper_funcs.cleanup_writeback_job

The documentation was pulled from the changelong introducing the
callbacks, originally written by Laurent.

Addign the missing documentation fixes the following warnings:
drm_modeset_helper_vtables.h:1052: warning: Function parameter or member 'prepare_writeback_job' not described in 'drm_connector_helper_funcs'
drm_modeset_helper_vtables.h:1052: warning: Function parameter or member 'cleanup_writeback_job' not described in 'drm_connector_helper_funcs'

Signed-off-by: Sam Ravnborg <sam at ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
Cc: Liviu Dudau <liviu.dudau at arm.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: David Airlie <airlied at linux.ie>
---
 include/drm/drm_modeset_helper_vtables.h | 31 ++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 7c20b1c8b6a7..c51bca1ffec7 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -1075,8 +1075,39 @@ struct drm_connector_helper_funcs {
 	void (*atomic_commit)(struct drm_connector *connector,
 			      struct drm_connector_state *state);
 
+	/**
+	 * @prepare_writeback_job:
+	 *
+	 * As writeback jobs contain a framebuffer, drivers may need to
+	 * prepare and cleanup them the same way they can prepare and
+	 * cleanup framebuffers for planes.
+	 * This optional connector operation is used to support the
+	 * preparation of writeback jobs.
+	 * The job prepare operation is called from
+	 * drm_atomic_helper_prepare_planes() to avoid a new atomic commit
+	 * helper that would need to be called by all drivers not using
+	 * drm_atomic_helper_commit().
+	 *
+	 * This hook is optional.
+	 *
+	 * This callback is used by the atomic modeset helpers.
+	 */
 	int (*prepare_writeback_job)(struct drm_writeback_connector *connector,
 				     struct drm_writeback_job *job);
+	/**
+	 * @cleanup_writeback_job:
+	 *
+	 * This optional connector operation is used to support the
+	 * cleanup of writeback jobs.
+	 * The job cleanup operation is called from the existing
+	 * drm_writeback_cleanup_job() function, invoked both when
+	 * destroying the job as part of a aborted commit, or when
+	 * the job completes.
+	 *
+	 * This hook is optional.
+	 *
+	 * This callback is used by the atomic modeset helpers.
+	 */
 	void (*cleanup_writeback_job)(struct drm_writeback_connector *connector,
 				      struct drm_writeback_job *job);
 };
-- 
2.20.1