[Intel-wired-lan] [PATCH 1/1] ixgbe: force to synchronize reporting "link on" and getting speed and duplex

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

On Wed, 2015-12-23 at 14:46 +0800, zyjzyj2000 at gmail.com wrote:
> From: Zhu Yanjun <zyjzyj2000@gmail.com>
> 
> In X540 NIC, there is a time span between reporting "link on" and
> getting the speed and duplex. To a bonding driver in 802.3ad mode,
> this time span will make it not work well if the time span is big
> enough. The big time span will make bonding driver change the state
> of
> the slave device to up while the speed and duplex of the slave device
> can not be gotten. Later the bonding driver will not have change to
> get the speed and duplex of the slave device. The speed and duplex of
> the slave device are important to a bonding driver in 802.3ad mode.
> 
> To 82599_SFP NIC and other kinds of NICs, this problem does
> not exist. As such, it is necessary for X540 to report"link on" when
> the link speed is not IXGBE_LINK_SPEED_UNKNOWN.
> 
> Signed-off-by: Zhu Yanjun <zyjzyj2000@gmail.com>
> ---
> ?drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |???16
> +++++++++++++++-
> ?1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index aed8d02..cb9d310 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -6479,7 +6479,21 @@ static void ixgbe_watchdog_link_is_up(struct
> ixgbe_adapter *adapter)
> ?	???????(flow_rx ? "RX" :
> ?	???????(flow_tx ? "TX" : "None"))));
> ?
> -	netif_carrier_on(netdev);
> +	/*
> +	?* In X540 NIC, there is a time span between reporting "link
> on"
> +	?* and getting the speed and duplex. To a bonding driver in
> 802.3ad
> +	?* mode, this time span will make it not work well if the
> time span
> +	?* is big enough. To 82599_SFP NIC and other kinds of NICs,
> this
> +	?* problem does not exist. As such, it is better for X540 to
> report
> +	?* "link on" when the link speed is not
> IXGBE_LINK_SPEED_UNKNOWN.
> +	?*/
> +	if ((hw->mac.type == ixgbe_mac_X540) &&
> +	????(link_speed != IXGBE_LINK_SPEED_UNKNOWN)) {
> +		netif_carrier_on(netdev);
> +	} else {
> +		netif_carrier_on(netdev);
> +	}
> +
> ?	ixgbe_check_vf_rate_limit(adapter);
> ?
> ?	/* enable transmits */

This patch only adds a needless test before
calling?netif_carrier_on(netdev), since the call happens no matter the
branch you take, it appears your running into a timing issue. ?So
adding a wait() before calling?netif_carrier_on(netdev) will accomplish
the same result and you do not have to add a useless test.
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