media: v4l2-fwnode: Defaults may not override endpoint configuration in firmware

The lack of defaults provided by the caller to
v4l2_fwnode_endpoint_parse() signals the use of the default lane mapping.
The default lane mapping must not be used however if the firmmare contains
the lane mapping. Disable the default lane mapping in that case, and
improve the debug messages telling of the use of the defaults.

This was missed previously since the default mapping will only unsed in
this case if the bus type is set, and no driver did both while still
needing the lane mapping configuration.

Fixes: b4357d21 ("media: v4l: fwnode: Support default CSI-2 lane mapping for drivers")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

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

@@ -163,7 +163,7 @@ static int v4l2_fwnode_endpoint_parse_csi2_bus(struct fwnode_handle *fwnode,
 		}
 
 		if (use_default_lane_mapping)
-			pr_debug("using default lane mapping\n");
+			pr_debug("no lane mapping given, using defaults\n");
 	}
 
 	rval = fwnode_property_read_u32_array(fwnode, "data-lanes", NULL, 0);
@@ -175,6 +175,10 @@ static int v4l2_fwnode_endpoint_parse_csi2_bus(struct fwnode_handle *fwnode,
 					       num_data_lanes);
 
 		have_data_lanes = true;
+		if (use_default_lane_mapping) {
+			pr_debug("data-lanes property exists; disabling default mapping\n");
+			use_default_lane_mapping = false;
+		}
 	}
 
 	for (i = 0; i < num_data_lanes; i++) {