net/netdev/netdev_register.c: Add some comments.

This commit adds some short comments to explain some perplexing logic of PR #1047.
This commit is contained in:
Gregory Nutt 2020-05-15 07:06:50 -06:00 committed by Abdelatif Guettouche
parent 87af256ad6
commit 35efcee5c9

View File

@ -1,36 +1,20 @@
/**************************************************************************** /****************************************************************************
* net/netdev/netdev_register.c * net/netdev/netdev_register.c
* *
* Copyright (C) 2007-2012, 2014-2015, 2017-2018 Gregory Nutt. All rights * Licensed to the Apache Software Foundation (ASF) under one or more
* reserved. * contributor license agreements. See the NOTICE file distributed with
* Author: Gregory Nutt <gnutt@nuttx.org> * this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
* *
* Redistribution and use in source and binary forms, with or without * http://www.apache.org/licenses/LICENSE-2.0
* modification, are permitted provided that the following conditions
* are met:
* *
* 1. Redistributions of source code must retain the above copyright * Unless required by applicable law or agreed to in writing, software
* notice, this list of conditions and the following disclaimer. * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* 2. Redistributions in binary form must reproduce the above copyright * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* notice, this list of conditions and the following disclaimer in * License for the specific language governing permissions and limitations
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* distribution.
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*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* *
****************************************************************************/ ****************************************************************************/
@ -335,7 +319,11 @@ int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)
return -EINVAL; return -EINVAL;
} }
/* Update the package length */ /* Update the package length. A network driver may provide custom
* values for MAC header length and for the maximum packet size. Some
* driver implementations (for example, the simulator) will require
* dynamic MTU calculations to support tunneling (as an example).
*/
if (dev->d_llhdrlen == 0) if (dev->d_llhdrlen == 0)
{ {