[PATCH v2] media: media-entity: make media_entity_cleanup() a no-op macro without MC

[Zixin Wang <w1355457260@gmail.com>]

Without CONFIG_MEDIA_CONTROLLER, struct v4l2_subdev has no entity member.
Calls such as media_entity_cleanup(&sd->entity) therefore fail to
compile even though the function does nothing:

  drivers/media/i2c/cx25840/cx25840-core.c:3964:41: error:
  'struct v4l2_subdev' has no member named 'entity'

Turn media_entity_cleanup() into a macro that discards its argument when
CONFIG_MEDIA_CONTROLLER is disabled.  This fixes the cx25840 build and
any other caller passing a member that only exists with the media
controller API enabled.

Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Fixes: 634be628b5cc ("media: i2c: cx25840-core: Add missing media_entity_cleanup()")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=222245
Signed-off-by: Zixin Wang <w1355457260@gmail.com>
---

Notes:
    Hi Sakari, thanks for the review and the suggestion.
    
    v2:
    - Make media_entity_cleanup() a no-op macro without
      CONFIG_MEDIA_CONTROLLER instead of guarding each caller (suggested by
      Sakari).
    
    AI assistance: the change and this changelog were drafted with the Qoder
    coding assistant; the sender reviewed it and ran the builds with
    CONFIG_MEDIA_CONTROLLER=n and =y.

 include/media/media-entity.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index fa393e840669..400e08598dd6 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -729,9 +729,13 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
  * zeroed but that has not been initialized with media_entity_pads_init() is
  * valid and is a no-op.
  */
+#ifdef CONFIG_MEDIA_CONTROLLER
 static inline void media_entity_cleanup(struct media_entity *entity)
 {
 }
+#else
+#define media_entity_cleanup(...)	do { } while (0)
+#endif
 
 /**
  * media_get_pad_index() - retrieves a pad index from an entity
-- 
2.56.1