As described in https://bugzilla.kernel.org/show_bug.cgi?id=218642, Intel I219-LM reports link up -> link down -> link up after hot-plugging the Ethernet cable.
The problem is because the unstable behavior of Link Status bit in PHY Status Register of some e1000e NIC. When we re-plug the cable, the e1000e_phy_has_link_generic() (called after the Link-Status-Changed interrupt) has read this bit with 1->0->1 (1=link up, 0=link down) and e1000e reports it to net device layer respectively. This patch solves the problem by passing polling delays on e1000e_phy_has_link_generic() so that it will not get the unstable states of Link Status bit. Link: https://bugzilla.kernel.org/show_bug.cgi?id=218642 Fixes: 7d3cabbcc86 ("e1000e: disable K1 at 1000Mbps for 82577/82578") Signed-off-by: Ricky Wu <[email protected]> --- In v2: * Split the sleep codes part into PATCHSET [1/2] --- drivers/net/ethernet/intel/e1000e/ich8lan.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c index f9e94be36e97..68f5698a22b0 100644 --- a/drivers/net/ethernet/intel/e1000e/ich8lan.c +++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c @@ -1428,7 +1428,17 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw) * link. If so, then we want to get the current speed/duplex * of the PHY. */ - ret_val = e1000e_phy_has_link_generic(hw, 1, 0, &link); + /* We've seen that I219-LM sometimes has link fluctuations + * (link up -> link down -> link up) after hot-plugging the cable. + * The problem is caused by the instability of the Link Status bit + * (BMSR_LSTATUS) in MII Status Register. The average time between + * the first link up and link down is between 3~4 ms. + * Increasing the iteration times and setting up the delay to + * 100ms (which is safe) solves the problem. + * This behavior hasn't been seen on other NICs and also not being + * documented in datasheet/errata. + */ + ret_val = e1000e_phy_has_link_generic(hw, COPPER_LINK_UP_LIMIT, 100000, &link); if (ret_val) goto out; -- 2.40.1
