s390/qeth: clean up initial MTU determination

1. Drop the support for Token Ring,
2. use the ETH_DATA_LEN macro for the default L2 MTU,
3. handle OSM via the default case (as OSM is L2-only), and
4. document why the L3 MTU is reduced.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Julian Wiedmann 2017-10-18 17:40:18 +02:00 committed by David S. Miller
parent 83cf79a2fe
commit 6e6f472d92
1 changed files with 4 additions and 10 deletions

View File

@ -2219,18 +2219,12 @@ static int qeth_get_initial_mtu_for_card(struct qeth_card *card)
case QETH_CARD_TYPE_IQD:
return card->info.max_mtu;
case QETH_CARD_TYPE_OSD:
switch (card->info.link_type) {
case QETH_LINK_TYPE_HSTR:
case QETH_LINK_TYPE_LANE_TR:
return 2000;
default:
return card->options.layer2 ? 1500 : 1492;
}
case QETH_CARD_TYPE_OSM:
case QETH_CARD_TYPE_OSX:
return card->options.layer2 ? 1500 : 1492;
if (!card->options.layer2)
return ETH_DATA_LEN - 8; /* L3: allow for LLC + SNAP */
/* fall through */
default:
return 1500;
return ETH_DATA_LEN;
}
}