igb: workaround errata with wthresh on 82576
authorStephen Hemminger <shemminger@vyatta.com>
Thu, 30 May 2013 17:12:35 +0000 (10:12 -0700)
committerThomas Monjalon <thomas.monjalon@6wind.com>
Tue, 17 Sep 2013 12:09:23 +0000 (14:09 +0200)
commit7e9e49feea96f11740095aa2eacd991d092bc009
tree64f2d4faa9b83cc4a13f3a992183d16fb7a141a6
parent9b2027a70bf803791776de012bfbca7e545aca70
igb: workaround errata with wthresh on 82576

The 82576 has known issues which require the write threshold to be set to 1.
See:
http://download.intel.com/design/network/specupdt/82576_SPECUPDATE.pdf

If not then single packets will hang in transmit ring until more arrive.
Simple tests like ping will fail.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Reviewed-by: Vincent Jardin <vincent.jardin@6wind.com>
lib/librte_pmd_e1000/igb_rxtx.c