media: cadence: csi2rx: Add link validation

Add media link validation to make sure incorrectly configured pipelines
are caught.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Tested-by: Julien Massot <julien.massot@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jai Luthra <j-luthra@ti.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Author: Pratyush Yadav

drivers/media/platform/cadence/cdns-csi2rx.c

@@ -453,6 +453,10 @@ static const struct v4l2_subdev_ops csi2rx_subdev_ops = {
 	.pad		= &csi2rx_pad_ops,
 };
 
+static const struct media_entity_operations csi2rx_media_ops = {
+	.link_validate = v4l2_subdev_link_validate,
+};
+
 static int csi2rx_async_bound(struct v4l2_async_notifier *notifier,
 			      struct v4l2_subdev *s_subdev,
 			      struct v4l2_async_connection *asd)
@@ -669,6 +673,7 @@ static int csi2rx_probe(struct platform_device *pdev)
 	for (i = CSI2RX_PAD_SOURCE_STREAM0; i < CSI2RX_PAD_MAX; i++)
 		csi2rx->pads[i].flags = MEDIA_PAD_FL_SOURCE;
 	csi2rx->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+	csi2rx->subdev.entity.ops = &csi2rx_media_ops;
 
 	ret = media_entity_pads_init(&csi2rx->subdev.entity, CSI2RX_PAD_MAX,
 				     csi2rx->pads);