e1000e: NIC goes up and immediately goes down

commit b7ec70be01a87f2c85df3ae11046e74f9b67e323 upstream.

Found that commit d478eb44 was a bad commit.
If the link partner is transmitting codeword (even if NULL codeword),
then the RXCW.C bit will be set so check for RXCW.CW is unnecessary.
Ref: RH BZ 840642

Reported-by: Fabio Futigami <ffutigam@redhat.com>
Signed-off-by: Tushar Dave <tushar.n.dave@intel.com>
CC: Marcelo Ricardo Leitner <mleitner@redhat.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/intel/e1000e/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index 1f063dcd8f85e39c15da5d82c935113af8044ffb..b8e4fcb85b36c9238b3861588ff91d8c5ae34305 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -1601,10 +1601,8 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
                         * auto-negotiation in the TXCW register and disable
                         * forced link in the Device Control register in an
                         * attempt to auto-negotiate with our link partner.
-                        * If the partner code word is null, stop forcing
-                        * and restart auto negotiation.
                         */
-                       if ((rxcw & E1000_RXCW_C) || !(rxcw & E1000_RXCW_CW))  {
+                       if (rxcw & E1000_RXCW_C) {
                                /* Enable autoneg, and unforce link up */
                                ew32(TXCW, mac->txcw);
                                ew32(CTRL, (ctrl & ~E1000_CTRL_SLU));