diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 7c9dc28640bb..c68fc9fb7598 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -923,9 +923,8 @@ static int usb_serial_probe(struct usb_interface *interface,
 		port = serial->port[i];
 		if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
 			goto probe_error;
-		buffer_size = serial->type->bulk_out_size;
-		if (!buffer_size)
-			buffer_size = usb_endpoint_maxp(endpoint);
+		buffer_size = max_t(int, serial->type->bulk_out_size,
+						usb_endpoint_maxp(endpoint));
 		port->bulk_out_size = buffer_size;
 		port->bulk_out_endpointAddress = endpoint->bEndpointAddress;
 
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 704a1ab8240c..9bb547c7bce7 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -190,7 +190,8 @@ static inline void usb_set_serial_data(struct usb_serial *serial, void *data)
  * @num_ports: the number of different ports this device will have.
  * @bulk_in_size: minimum number of bytes to allocate for bulk-in buffer
  *	(0 = end-point size)
- * @bulk_out_size: bytes to allocate for bulk-out buffer (0 = end-point size)
+ * @bulk_out_size: minimum number of bytes to allocate for bulk-out buffer
+ *	(0 = end-point size)
  * @calc_num_ports: pointer to a function to determine how many ports this
  *	device has dynamically.  It will be called after the probe()
  *	callback is called, but before attach()