[PATCH 01/11] v4l: subdev: Extend default link validation to cover field order

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

The field order must match between the source and sink pads, or the sink
pad field order must be NONE. This allows connecting an interlaced
source to a bridge that has no hardware support for interlaced formats.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 058c1a6..752cca0 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -468,11 +468,20 @@ int v4l2_subdev_link_validate_default(struct v4l2_subdev *sd,
 				      struct v4l2_subdev_format *source_fmt,
 				      struct v4l2_subdev_format *sink_fmt)
 {
+	/* The width, height and code must match. */
 	if (source_fmt->format.width != sink_fmt->format.width
 	    || source_fmt->format.height != sink_fmt->format.height
 	    || source_fmt->format.code != sink_fmt->format.code)
 		return -EINVAL;
 
+	/* The field order must match, or the sink field order must be NONE
+	 * to support interlaced hardware connected to bridges that support
+	 * progressive formats only.
+	 */
+	if (source_fmt->format.field != sink_fmt->format.field &&
+	    sink_fmt->format.field != V4L2_FIELD_NONE)
+		return -EINVAL;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_link_validate_default);
-- 
1.8.5.5