coresight: Cleanup coresight_remove_conns

When a device is unregistered, we remove all connection
references to it, by searching the connection records of
all devices in the coresight bus, via coresight_remove_conns.
We could avoid searching if this device doesn't have an input
port (e.g, a source). Also document the purpose of the function.
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight.c

@@ -1096,10 +1096,21 @@ static int coresight_remove_match(struct device *dev, void *data)
 	return 0;
 }
 
+/*
+ * coresight_remove_conns - Remove references to this given devices
+ * from the connections of other devices.
+ */
 static void coresight_remove_conns(struct coresight_device *csdev)
 {
-	bus_for_each_dev(&coresight_bustype, NULL,
-			 csdev, coresight_remove_match);
+	/*
+	 * Another device will point to this device only if there is
+	 * an output port connected to this one. i.e, if the device
+	 * doesn't have at least one input port, there is no point
+	 * in searching all the devices.
+	 */
+	if (csdev->nr_inport)
+		bus_for_each_dev(&coresight_bustype, NULL,
+				 csdev, coresight_remove_match);
 }
 
 /**