netdev - Re: [PATCH net-next 2/3] net: fec: use mac-managed PHY PM

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Date:   Thu, 8 Apr 2021 07:59:30 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Joakim Zhang <qiangqing.zhang@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Fugang Duan <fugang.duan@....com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 2/3] net: fec: use mac-managed PHY PM

On 08.04.2021 07:45, Joakim Zhang wrote:
> 
>> -----Original Message-----
>> From: Heiner Kallweit <hkallweit1@...il.com>
>> Sent: 2021年4月7日 23:53
>> To: Andrew Lunn <andrew@...n.ch>; Russell King - ARM Linux
>> <linux@...linux.org.uk>; Jakub Kicinski <kuba@...nel.org>; David Miller
>> <davem@...emloft.net>; Fugang Duan <fugang.duan@....com>
>> Cc: netdev@...r.kernel.org; Joakim Zhang <qiangqing.zhang@....com>
>> Subject: [PATCH net-next 2/3] net: fec: use mac-managed PHY PM
>>
>> Use the new mac_managed_pm flag to work around an issue with KSZ8081
>> PHY that becomes unstable when a soft reset is triggered during aneg.
>>
>> Reported-by: Joakim Zhang <qiangqing.zhang@....com>
>> Tested-by: Joakim Zhang <qiangqing.zhang@....com>
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  drivers/net/ethernet/freescale/fec_main.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>> b/drivers/net/ethernet/freescale/fec_main.c
>> index 3db882322..70aea9c27 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -2048,6 +2048,8 @@ static int fec_enet_mii_probe(struct net_device
>> *ndev)
>>  	fep->link = 0;
>>  	fep->full_duplex = 0;
>>
>> +	phy_dev->mac_managed_pm = 1;
>> +
>>  	phy_attached_info(phy_dev);
>>
>>  	return 0;
>> @@ -3864,6 +3866,7 @@ static int __maybe_unused fec_resume(struct
>> device *dev)
>>  		netif_device_attach(ndev);
>>  		netif_tx_unlock_bh(ndev);
>>  		napi_enable(&fep->napi);
>> +		phy_init_hw(ndev->phydev);
> 
> 
> For now, I think we doesn't need to re-initialize PHY after MAC resume back, it also can be done by PHY driver if it needed.
> 
The PHY PM resume callback (that used to call phy_init_hw) is a no-op now.
So we have to call it from the MAC resume callback. Power to the PHY may be
off during system suspend, therefore it may be reset to power-on defaults.
That's why phy_init_hw() should be called, that includes calling the
PHY drivers config_init callback.

> Best Regards,
> Joakim Zhang
>>  		phy_start(ndev->phydev);
>>  	}
>>  	rtnl_unlock();
>> --
>> 2.31.1
>>
>