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authorTushar Dave <tushar.n.dave@intel.com>2012-07-12 08:56:56 +0000
committerBen Hutchings <ben@decadent.org.uk>2012-07-25 04:11:23 +0100
commitdf4372866de83261b79bf7af24c058649ed0f2eb (patch)
tree58950f03323c8a32745d88fdc90eba98c8b05389 /drivers/net/ethernet
parent154f4399c91b93519cd4a0ba0eceb21ced26c241 (diff)
e1000e: Correct link check logic for 82571 serdes
commit d0efa8f23a644f7cb7d1f8e78dd9a223efa412a3 upstream. SYNCH bit and IV bit of RXCW register are sticky. Before examining these bits, RXCW should be read twice to filter out one-time false events and have correct values for these bits. Incorrect values of these bits in link check logic can cause weird link stability issues if auto-negotiation fails. Reported-by: Dean Nelson <dnelson@redhat.com> Signed-off-by: Tushar Dave <tushar.n.dave@intel.com> Reviewed-by: Bruce Allan <bruce.w.allan@intel.com> Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/net/ethernet')
-rw-r--r--drivers/net/ethernet/intel/e1000e/82571.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/ethernet/intel/e1000e/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index e556fc3a3cf..3072d35cc4b 100644
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -1571,6 +1571,9 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
ctrl = er32(CTRL);
status = er32(STATUS);
rxcw = er32(RXCW);
+ /* SYNCH bit and IV bit are sticky */
+ udelay(10);
+ rxcw = er32(RXCW);
if ((rxcw & E1000_RXCW_SYNCH) && !(rxcw & E1000_RXCW_IV)) {