drm/plane-helper: Provide DRM_PLANE_NON_ATOMIC_FUNCS initializer macro

Provide DRM_PLANE_NON_ATOMIC_FUNCS, which initializes plane functions
of non-atomic drivers to default values. The macro is not supposed to
be used in new code, but helps with documenting and finding existing
users.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Lyude Paul <lyude@redhat.com> # nouveau
Link: https://patchwork.freedesktop.org/patch/msgid/20220909105947.6487-5-tzimmermann@suse.de

drivers/gpu/drm/drm_modeset_helper.c

@@ -108,9 +108,7 @@ static const uint32_t safe_modeset_formats[] = {
 };
 
 static const struct drm_plane_funcs primary_plane_funcs = {
-	.update_plane = drm_plane_helper_update_primary,
-	.disable_plane = drm_plane_helper_disable_primary,
-	.destroy = drm_plane_helper_destroy,
+	DRM_PLANE_NON_ATOMIC_FUNCS,
 };
 
 /**

drivers/gpu/drm/nouveau/dispnv04/crtc.c

@@ -1276,9 +1276,7 @@ static const uint32_t modeset_formats[] = {
 };
 
 static const struct drm_plane_funcs nv04_primary_plane_funcs = {
-	.update_plane = drm_plane_helper_update_primary,
-	.disable_plane = drm_plane_helper_disable_primary,
-	.destroy = drm_plane_helper_destroy,
+	DRM_PLANE_NON_ATOMIC_FUNCS,
 };
 
 static int nv04_crtc_vblank_handler(struct nvif_notify *notify)

include/drm/drm_plane_helper.h

@@ -43,4 +43,16 @@ int drm_plane_helper_disable_primary(struct drm_plane *plane,
 void drm_plane_helper_destroy(struct drm_plane *plane);
 int drm_plane_helper_atomic_check(struct drm_plane *plane, struct drm_atomic_state *state);
 
+/**
+ * DRM_PLANE_NON_ATOMIC_FUNCS - Default plane functions for non-atomic drivers
+ *
+ * This macro initializes plane functions for non-atomic drivers to default
+ * values. Non-atomic interfaces are deprecated and should not be used in new
+ * drivers.
+ */
+#define DRM_PLANE_NON_ATOMIC_FUNCS \
+	.update_plane = drm_plane_helper_update_primary, \
+	.disable_plane = drm_plane_helper_disable_primary, \
+	.destroy = drm_plane_helper_destroy
+
 #endif