[PATCH v5 20/23] media: imx: csi: Lookup upstream endpoint with imx_media_get_pad_fwnode

[Steve Longerbeam <slongerbeam@xxxxxxxxx>]

Fix the 1:1 port-id:pad-index assumption for the upstream subdevice, by
searching the upstream subdevice's endpoints for one that maps to the
pad's index. This is carried out by a new reverse mapping function
imx_media_get_pad_fwnode().

Signed-off-by: Steve Longerbeam <slongerbeam@xxxxxxxxx>
---
 drivers/staging/media/imx/imx-media-csi.c   | 22 ++++----------
 drivers/staging/media/imx/imx-media-utils.c | 33 +++++++++++++++++++++
 drivers/staging/media/imx/imx-media.h       |  1 +
 3 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index 303f92ef4d9c..a7640a5d7791 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -164,7 +164,7 @@ static inline bool requires_passthrough(struct v4l2_fwnode_endpoint *ep,
 static int csi_get_upstream_endpoint(struct csi_priv *priv,
 				     struct v4l2_fwnode_endpoint *ep)
 {
-	struct device_node *endpoint, *port;
+	struct fwnode_handle *endpoint;
 	struct v4l2_subdev *sd;
 	struct media_pad *pad;
 
@@ -205,23 +205,13 @@ static int csi_get_upstream_endpoint(struct csi_priv *priv,
 	if (!pad)
 		return -ENODEV;
 
-	sd = media_entity_to_v4l2_subdev(pad->entity);
+	endpoint = imx_media_get_pad_fwnode(pad);
+	if (IS_ERR(endpoint))
+		return PTR_ERR(endpoint);
 
-	/*
-	 * NOTE: this assumes an OF-graph port id is the same as a
-	 * media pad index.
-	 */
-	port = of_graph_get_port_by_id(sd->dev->of_node, pad->index);
-	if (!port)
-		return -ENODEV;
-
-	endpoint = of_get_next_child(port, NULL);
-	of_node_put(port);
-	if (!endpoint)
-		return -ENODEV;
+	v4l2_fwnode_endpoint_parse(endpoint, ep);
 
-	v4l2_fwnode_endpoint_parse(of_fwnode_handle(endpoint), ep);
-	of_node_put(endpoint);
+	fwnode_handle_put(endpoint);
 
 	return 0;
 }
diff --git a/drivers/staging/media/imx/imx-media-utils.c b/drivers/staging/media/imx/imx-media-utils.c
index fae981698c49..cc47591a5f0b 100644
--- a/drivers/staging/media/imx/imx-media-utils.c
+++ b/drivers/staging/media/imx/imx-media-utils.c
@@ -923,6 +923,39 @@ imx_media_pipeline_video_device(struct media_entity *start_entity,
 }
 EXPORT_SYMBOL_GPL(imx_media_pipeline_video_device);
 
+/*
+ * Find a fwnode endpoint that maps to the given subdevice's pad.
+ * If there are multiple endpoints that map to the pad, only the
+ * first endpoint encountered is returned.
+ *
+ * On success the refcount of the returned fwnode endpoint is
+ * incremented.
+ */
+struct fwnode_handle *imx_media_get_pad_fwnode(struct media_pad *pad)
+{
+	struct fwnode_handle *endpoint;
+	struct v4l2_subdev *sd;
+
+	if (!is_media_entity_v4l2_subdev(pad->entity))
+		return ERR_PTR(-ENODEV);
+
+	sd = media_entity_to_v4l2_subdev(pad->entity);
+
+	fwnode_graph_for_each_endpoint(dev_fwnode(sd->dev), endpoint) {
+		int pad_idx = media_entity_get_fwnode_pad(&sd->entity,
+							  endpoint,
+							  pad->flags);
+		if (pad_idx < 0)
+			continue;
+
+		if (pad_idx == pad->index)
+			return endpoint;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(imx_media_get_pad_fwnode);
+
 /*
  * Turn current pipeline streaming on/off starting from entity.
  */
diff --git a/drivers/staging/media/imx/imx-media.h b/drivers/staging/media/imx/imx-media.h
index d89026bb99a8..058a41e3d941 100644
--- a/drivers/staging/media/imx/imx-media.h
+++ b/drivers/staging/media/imx/imx-media.h
@@ -201,6 +201,7 @@ imx_media_pipeline_subdev(struct media_entity *start_entity, u32 grp_id,
 struct video_device *
 imx_media_pipeline_video_device(struct media_entity *start_entity,
 				enum v4l2_buf_type buftype, bool upstream);
+struct fwnode_handle *imx_media_get_pad_fwnode(struct media_pad *pad);
 
 struct imx_media_dma_buf {
 	void          *virt;
-- 
2.17.1