Implement the .get_frame_desc() callback to fetch information from the
remote endpoint.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/media/platform/synopsys/dw-mipi-csi2rx.c | 25 ++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
index 61cd7f491b3d5b8a37707b23ca03ce709b40a79f..4ad4e3b23448affeeaa932a706653818ba4019ba 100644
--- a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
+++ b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
@@ -70,6 +70,8 @@ struct dw_mipi_csi2rx_device {
 	struct v4l2_async_notifier notifier;
 	struct v4l2_subdev sd;
 
+	struct v4l2_subdev *remote_source;
+
 	enum v4l2_mbus_type bus_type;
 	u32 lanes_num;
 };
@@ -431,10 +433,31 @@ static int dw_mipi_csi2rx_disable_streams(struct v4l2_subdev *sd,
 	return ret;
 }
 
+static int
+dw_mipi_csi2rx_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+			      struct v4l2_mbus_frame_desc *fd)
+{
+	struct dw_mipi_csi2rx_device *csi2 = to_csi2(sd);
+	struct media_pad *remote_pad;
+
+	if (!csi2->remote_source)
+		return -ENODEV;
+
+	remote_pad = media_pad_remote_pad_unique(&csi2->pads[DW_MIPI_CSI2RX_PAD_SINK]);
+	if (IS_ERR(remote_pad)) {
+		dev_err(csi2->dev, "can't get source pad of %s (%pe)\n",
+			csi2->remote_source->name, remote_pad);
+		return PTR_ERR(remote_pad);
+	}
+	return v4l2_subdev_call(csi2->remote_source, pad, get_frame_desc,
+				remote_pad->index, fd);
+}
+
 static const struct v4l2_subdev_pad_ops dw_mipi_csi2rx_pad_ops = {
 	.enum_mbus_code = dw_mipi_csi2rx_enum_mbus_code,
 	.get_fmt = v4l2_subdev_get_fmt,
 	.set_fmt = dw_mipi_csi2rx_set_fmt,
+	.get_frame_desc = dw_mipi_csi2rx_get_frame_desc,
 	.set_routing = dw_mipi_csi2rx_set_routing,
 	.enable_streams = dw_mipi_csi2rx_enable_streams,
 	.disable_streams = dw_mipi_csi2rx_disable_streams,
@@ -487,6 +510,8 @@ static int dw_mipi_csi2rx_notifier_bound(struct v4l2_async_notifier *notifier,
 		return ret;
 	}
 
+	csi2->remote_source = sd;
+
 	return 0;
 }
 

-- 
2.43.0