netdev - Re: [PATCH 4/4] amd-xgbe: Fix network fluctuations when using 1G BELFUSE SFP

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Message-ID: <ead767df-ca25-34f6-2518-febc27a642c1@amd.com>
Date:   Fri, 12 Feb 2021 13:05:27 -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 4/4] amd-xgbe: Fix network fluctuations when using 1G
 BELFUSE SFP

On 2/12/21 12:00 PM, Shyam Sundar S K wrote:
> Frequent link up/down events can happen when a Bel Fuse SFP part is
> connected to the amd-xgbe device. Try to avoid the frequent link
> issues by resetting the PHY as documented in Bel Fuse SFP datasheets.
> 
> 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: tag as previous patch.

With that addressed,

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

> ---
>   drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> index 1bb468ac9635..e328fd9bd294 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> @@ -922,6 +922,12 @@ static bool xgbe_phy_belfuse_phy_quirks(struct xgbe_prv_data *pdata)
>   	if ((phy_id & 0xfffffff0) != 0x03625d10)
>   		return false;
>   
> +	/* Reset PHY - wait for self-clearing reset bit to clear */
> +	reg = phy_read(phy_data->phydev, 0x00);
> +	phy_write(phy_data->phydev, 0x00, reg | 0x8000);
> +	read_poll_timeout(phy_read, reg, !(reg & 0x8000) || reg < 0,
> +			  10000, 50000, true, phy_data->phydev, 0x0);
> +
>   	/* Disable RGMII mode */
>   	phy_write(phy_data->phydev, 0x18, 0x7007);
>   	reg = phy_read(phy_data->phydev, 0x18);
>