IXGBE_RMCS_TFCE_802_3X
rmcs_reg &= ~(IXGBE_RMCS_TFCE_PRIORITY | IXGBE_RMCS_TFCE_802_3X);
rmcs_reg |= IXGBE_RMCS_TFCE_802_3X;
rmcs_reg |= IXGBE_RMCS_TFCE_802_3X;
reg &= ~IXGBE_RMCS_TFCE_802_3X;
flow_tx = !!(rmcs & IXGBE_RMCS_TFCE_802_3X);