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authorStefan Assmann <sassmann@kpanic.de>2012-08-07 00:45:57 -0700
committerPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>2012-08-07 00:47:51 -0700
commit119b0e0351bcdb7833f368781e6241ff283b49e5 (patch)
treefec590cde6e8e5e5dafa0c6998262d3bbb8a98bb /drivers/net
parenteca90f550494171f54f8a700caee65ec16455a5b (diff)
downloadop-kernel-dev-119b0e0351bcdb7833f368781e6241ff283b49e5.zip
op-kernel-dev-119b0e0351bcdb7833f368781e6241ff283b49e5.tar.gz
igb: add delay to allow igb loopback test to succeed on 8086:10c9
Some 8086:10c9 NICs have a problem completing the ethtool loopback test. The result looks like this: ethtool -t eth1 The test result is FAIL The test extra info: Register test (offline) 0 Eeprom test (offline) 0 Interrupt test (offline) 0 Loopback test (offline) 13 Link test (on/offline) 0 A bisect clearly points to commit a95a07445ee97a2fef65befafbadcc30ca1bd145. However that seems to only trigger the bug. While adding some printk the problem disappeared, so this might be a timing issue. After some trial and error I discovered that adding a small delay just before igb_write_phy_reg() in igb_integrated_phy_loopback() allows the loopback test to succeed. I was unable to figure out the root cause so far but I expect it to be somewhere in the following executing path igb_integrated_phy_loopback ->igb_write_phy_reg_igp ->igb_write_phy_reg_mdic ->igb_acquire_phy_82575 ->igb_acquire_swfw_sync_82575 The problem could only be observed on 8086:10c9 NICs so far and not all of them show the behaviour. I did not restrict the workaround to this type of NIC as it should do no harm to other igb NICs. With the patch below the loopback test succeeded 500 times in a row using a NIC that would otherwise fail. Signed-off-by: Stefan Assmann <sassmann@kpanic.de> Tested-by: Aaron Brown <aaron.f.brown@intel.com> Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/intel/igb/igb_ethtool.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
index 90550f5..7059111 100644
--- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
+++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
@@ -1498,6 +1498,9 @@ static int igb_integrated_phy_loopback(struct igb_adapter *adapter)
break;
}
+ /* add small delay to avoid loopback test failure */
+ msleep(50);
+
/* force 1000, set loopback */
igb_write_phy_reg(hw, PHY_CONTROL, 0x4140);
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