linux-kernel - Re: [PATCH V2 net 2/2] net: hns: fix fake link up on xge port

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Date:   Mon, 4 Dec 2023 11:19:59 +0100
From:   Wojciech Drewek <wojciech.drewek@...el.com>
To:     Jijie Shao <shaojijie@...wei.com>, <yisen.zhuang@...wei.com>,
        <salil.mehta@...wei.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>
CC:     <shenjian15@...wei.com>, <wangjie125@...wei.com>,
        <liuyonglong@...wei.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 net 2/2] net: hns: fix fake link up on xge port



On 04.12.2023 02:10, Jijie Shao wrote:
> From: Yonglong Liu <liuyonglong@...wei.com>
> 
> If a xge port just connect with an optical module and no fiber,
> it may have a fake link up because there may be interference on
> the hardware. This patch adds an anti-shake to avoid the problem.
> And the time of anti-shake is base on tests.
> 
> Fixes: b917078c1c10 ("net: hns: Add ACPI support to check SFP present")
> Signed-off-by: Yonglong Liu <liuyonglong@...wei.com>
> Signed-off-by: Jijie Shao <shaojijie@...wei.com>
> ---
>  .../net/ethernet/hisilicon/hns/hns_dsaf_mac.c | 29 +++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c
> index 928d934cb21a..c3abb14edd51 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c
> @@ -66,6 +66,27 @@ static enum mac_mode hns_get_enet_interface(const struct hns_mac_cb *mac_cb)
>  	}
>  }
>  
> +static void hns_mac_link_anti_shake(struct mac_driver *mac_ctrl_drv,
> +				    u32 *link_status)
> +{

It would be cleaner to return the link status than using output arg IMO

> +#define HNS_MAC_LINK_WAIT_TIME 5
> +#define HNS_MAC_LINK_WAIT_CNT 40
> +
> +	int i;
> +
> +	if (!mac_ctrl_drv->get_link_status) {
> +		*link_status = 0;
> +		return;
> +	}
> +
> +	for (i = 0; i < HNS_MAC_LINK_WAIT_CNT; i++) {
> +		msleep(HNS_MAC_LINK_WAIT_TIME);
> +		mac_ctrl_drv->get_link_status(mac_ctrl_drv, link_status);
> +		if (!*link_status)
> +			break;
> +	}
> +}
> +
>  void hns_mac_get_link_status(struct hns_mac_cb *mac_cb, u32 *link_status)
>  {
>  	struct mac_driver *mac_ctrl_drv;
> @@ -83,6 +104,14 @@ void hns_mac_get_link_status(struct hns_mac_cb *mac_cb, u32 *link_status)
>  							       &sfp_prsnt);
>  		if (!ret)
>  			*link_status = *link_status && sfp_prsnt;
> +
> +		/* for FIBER port, it may have a fake link up.
> +		 * when the link status changes from down to up, we need to do
> +		 * anti-shake. the anti-shake time is base on tests.
> +		 * only FIBER port need to do this.
> +		 */
> +		if (*link_status && !mac_cb->link)
> +			hns_mac_link_anti_shake(mac_ctrl_drv, link_status);
>  	}
>  
>  	mac_cb->link = *link_status;