Re: [PATCH v4] net/ixgbe: ensure link status is updated

[Roger B Melton <rmelton@cisco.com>]

Hi Laurent/Wei,

As I continue to integrate DPDK 17.05 into my application, I have hit 
another issue with this patch while testing in a VM with multispeed 
fiber ixgbe PCI passthrough.  My application periodically invokes 
rte_eth_link_get_nowait() to detect link state changes.  If the link is 
down (no cable or far end disabled), ixgbe_setup_link() will not return 
for ~1.3seconds due to the link setup algorithm in 
ixgbe_common.c:ixgbe_multispeed_fiber():

+	if ((intr->flags & IXGBE_FLAG_NEED_LINK_CONFIG) &&
+		hw->mac.ops.get_media_type(hw) == ixgbe_media_type_fiber) {
+		speed = hw->phy.autoneg_advertised;
+		if (!speed)
+			ixgbe_get_link_capabilities(hw, &speed, &autoneg);
+		ixgbe_setup_link(hw, speed, true); +	}
+

I have two questions:

  * Shouldn't we avoid the link setup cost if the caller has specified
    not to wait_to_complete?
  * If the concern is speed may not be properly configured, shouldn't
    the link setup be deferred until state changes link up thus
    minimizing the delays enforced in ixgbe_multispeed_fiber()?


Regards,
-Roger




On 4/27/17 11:03 AM, Laurent Hardy wrote:
> In case of fiber and link speed set to 1Gb at peer side (with autoneg
> or with defined speed), link status could be not properly updated at
> time cable is plugged-in.
> Indeed if cable was not plugged when device has been configured and
> started then link status will not be updated properly with new speed
> as no link setup will be triggered.
>
> To avoid this issue, IXGBE_FLAG_NEED_LINK_CONFIG is set to try a link
> setup each time link_update() is triggered and current link status is
> down. When cable is plugged-in, link setup will be performed via
> ixgbe_setup_link().
>
> Signed-off-by: Laurent Hardy <laurent.hardy@6wind.com>
> ---
> Hi Wei, please find enclosed patch v4, tested using testpmd.
>
> v1 -> v2:
> - rebase on top of head (change flag to 1<<4)
> - fix regression with copper links: only update link for fiber links
>
> v2 -> v3:
> - remove unnescessary check on speed mask if autoneg is false
>
> v3 -> v4:
> - remove default speed set to 10Gb if autoneg is false, rely on
> ixgbe_get_link_capabilities( ) instead.
> ---
>   drivers/net/ixgbe/ixgbe_ethdev.c | 14 ++++++++++++++
>   drivers/net/ixgbe/ixgbe_ethdev.h |  1 +
>   2 files changed, 15 insertions(+)
>
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
> index 7b856bb..8a0c0a7 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> @@ -3782,8 +3782,12 @@ ixgbe_dev_link_update(struct rte_eth_dev *dev, int wait_to_complete)
>   	struct ixgbe_hw *hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
>   	struct rte_eth_link link, old;
>   	ixgbe_link_speed link_speed = IXGBE_LINK_SPEED_UNKNOWN;
> +	struct ixgbe_interrupt *intr =
> +		IXGBE_DEV_PRIVATE_TO_INTR(dev->data->dev_private);
>   	int link_up;
>   	int diag;
> +	u32 speed = 0;
> +	bool autoneg = false;
>   
>   	link.link_status = ETH_LINK_DOWN;
>   	link.link_speed = 0;
> @@ -3793,6 +3797,14 @@ ixgbe_dev_link_update(struct rte_eth_dev *dev, int wait_to_complete)
>   
>   	hw->mac.get_link_status = true;
>   
> +	if ((intr->flags & IXGBE_FLAG_NEED_LINK_CONFIG) &&
> +		hw->mac.ops.get_media_type(hw) == ixgbe_media_type_fiber) {
> +		speed = hw->phy.autoneg_advertised;
> +		if (!speed)
> +			ixgbe_get_link_capabilities(hw, &speed, &autoneg);
> +		ixgbe_setup_link(hw, speed, true);
> +	}
> +
>   	/* check if it needs to wait to complete, if lsc interrupt is enabled */
>   	if (wait_to_complete == 0 || dev->data->dev_conf.intr_conf.lsc != 0)
>   		diag = ixgbe_check_link(hw, &link_speed, &link_up, 0);
> @@ -3810,10 +3822,12 @@ ixgbe_dev_link_update(struct rte_eth_dev *dev, int wait_to_complete)
>   
>   	if (link_up == 0) {
>   		rte_ixgbe_dev_atomic_write_link_status(dev, &link);
> +		intr->flags |= IXGBE_FLAG_NEED_LINK_CONFIG;
>   		if (link.link_status == old.link_status)
>   			return -1;
>   		return 0;
>   	}
> +	intr->flags &= ~IXGBE_FLAG_NEED_LINK_CONFIG;
>   	link.link_status = ETH_LINK_UP;
>   	link.link_duplex = ETH_LINK_FULL_DUPLEX;
>   
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.h b/drivers/net/ixgbe/ixgbe_ethdev.h
> index 5176b02..b576a6f 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.h
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.h
> @@ -45,6 +45,7 @@
>   #define IXGBE_FLAG_MAILBOX          (uint32_t)(1 << 1)
>   #define IXGBE_FLAG_PHY_INTERRUPT    (uint32_t)(1 << 2)
>   #define IXGBE_FLAG_MACSEC           (uint32_t)(1 << 3)
> +#define IXGBE_FLAG_NEED_LINK_CONFIG (uint32_t)(1 << 4)
>   
>   /*
>    * Defines that were not part of ixgbe_type.h as they are not used by the