netdev - Re: [PATCH 3/4] amd-xgbe: Reset link when the link never comes back

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Message-ID: <9aef8251-0350-7321-f5ab-6158466ea809@amd.com>
Date:   Fri, 12 Feb 2021 13:01:08 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Sudheesh.Mavila@....com
Subject: Re: [PATCH 3/4] amd-xgbe: Reset link when the link never comes back

On 2/12/21 12:00 PM, Shyam Sundar S K wrote:
> Normally, auto negotiation and reconnect should be automatically done by
> the hardware. But there seems to be an issue where auto negotiation has
> to be restarted manually. This happens because of link training and so
> even though still connected to the partner the link never "comes back".
> This would need a reset to recover.

This last sentence is strange. Are you meaning to say this needs to 
restart auto-negotiation?

Please mention this pertains only to a backplane connection mode.

> 
> Also, a change in xgbe-mdio is needed to get ethtool to recognize the
> link down and get the link change message.
> 
> Signed-off-by: Sudheesh Mavila <sudheesh.mavila@....com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>

Same comment about Co-developed-by: as previous patch.

With those addressed,

Acked-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>   drivers/net/ethernet/amd/xgbe/xgbe-mdio.c   | 2 +-
>   drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c | 8 ++++++++
>   2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> index 19ee4db0156d..4e97b4869522 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> @@ -1345,7 +1345,7 @@ static void xgbe_phy_status(struct xgbe_prv_data *pdata)
>   							     &an_restart);
>   	if (an_restart) {
>   		xgbe_phy_config_aneg(pdata);
> -		return;
> +		goto adjust_link;
>   	}
>   
>   	if (pdata->phy.link) {
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> index 489f1f86df99..1bb468ac9635 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> @@ -2607,6 +2607,14 @@ static int xgbe_phy_link_status(struct xgbe_prv_data *pdata, int *an_restart)
>   	if (reg & MDIO_STAT1_LSTATUS)
>   		return 1;
>   
> +	if (pdata->phy.autoneg == AUTONEG_ENABLE &&
> +	    phy_data->port_mode == XGBE_PORT_MODE_BACKPLANE) {
> +		if (!test_bit(XGBE_LINK_INIT, &pdata->dev_state)) {
> +			netif_carrier_off(pdata->netdev);
> +			*an_restart = 1;
> +		}
> +	}
> +
>   	/* No link, attempt a receiver reset cycle */
>   	if (phy_data->rrc_count++ > XGBE_RRC_FREQUENCY) {
>   		phy_data->rrc_count = 0;
>