media: v4l2-async: Log message in case of heterogeneous fwnode match

When a notifier supplies a device fwnode and a subdev supplies an
endpoint fwnode, incorrect matches may occur if multiple subdevs
correspond to the same device fwnode. This can't be handled
transparently in the framework, and requires the notifier to switch to
endpoint fwnodes. Log a message to notify of this problem. A second
message is added to help accelerating the transition to endpoint
matching.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/v4l2-core/v4l2-async.c

@@ -77,6 +77,7 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
 	struct fwnode_handle *dev_fwnode;
 	bool asd_fwnode_is_ep;
 	bool sd_fwnode_is_ep;
+	struct device *dev;
 
 	/*
 	 * Both the subdev and the async subdev can provide either an endpoint
@@ -114,7 +115,28 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
 
 	fwnode_handle_put(dev_fwnode);
 
-	return dev_fwnode == other_fwnode;
+	if (dev_fwnode != other_fwnode)
+		return false;
+
+	/*
+	 * We have a heterogeneous match. Retrieve the struct device of the side
+	 * that matched on a device fwnode to print its driver name.
+	 */
+	if (sd_fwnode_is_ep)
+		dev = notifier->v4l2_dev ? notifier->v4l2_dev->dev
+		    : notifier->sd->dev;
+	else
+		dev = sd->dev;
+
+	if (dev && dev->driver) {
+		if (sd_fwnode_is_ep)
+			dev_warn(dev, "Driver %s uses device fwnode, incorrect match may occur\n",
+				 dev->driver->name);
+		dev_notice(dev, "Consider updating driver %s to match on endpoints\n",
+			   dev->driver->name);
+	}
+
+	return true;
 }
 
 static bool match_custom(struct v4l2_async_notifier *notifier,