[PATCH 08/17] media: v4l2-subdev: Always return at least one frame descriptor

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Make v4l2_subdev_get_frame_desc() return at least one frame descriptor
entry or an error. Empty frame descriptors aren't useful for callers so
callers can now omit this check.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 5 +++++
 include/media/v4l2-subdev.h           | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 9d7f616ab7ea..b92ae87fa5d0 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -2709,6 +2709,11 @@ static int __v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad
 			return -EINVAL;
 		}
 
+		if (!desc->num_entries) {
+			dev_dbg(sd->dev, "no frame descriptor entries\n");
+			return -EINVAL;
+		}
+
 		return ret;
 	}
 
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 6e40420c2fcc..8b10dcab5590 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -1816,6 +1816,8 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
  * struct v4l2_mbus_frame_desc *desc __free(v4l2_subdev_free_frame_desc) =
  *	v4l2_subdev_get_frame_desc(sd, pad, desc);
  *
+ * The returned frame descriptor will contain at least one entry.
+ *
  * Return: The frame descriptor on success or a negative error code on failure.
  */
 struct v4l2_mbus_frame_desc *
-- 
2.47.3