netdev - Re: [RFC PATCH net-next] net: phy: force phy suspend when calling phy

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Date:   Tue, 27 Aug 2019 21:41:58 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     "shenjian (K)" <shenjian15@...wei.com>, andrew@...n.ch,
        f.fainelli@...il.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, forest.zhouchang@...wei.com,
        linuxarm@...wei.com
Subject: Re: [RFC PATCH net-next] net: phy: force phy suspend when calling
 phy_stop

On 27.08.2019 10:29, shenjian (K) wrote:
> 
> 
> 在 2019/8/27 13:51, Heiner Kallweit 写道:
>> On 27.08.2019 04:47, Jian Shen wrote:
>>> Some ethernet drivers may call phy_start() and phy_stop() from
>>> ndo_open and ndo_close() respectively.
>>>
>>> When network cable is unconnected, and operate like below:
>>> step 1: ifconfig ethX up -> ndo_open -> phy_start ->start
>>> autoneg, and phy is no link.
>>> step 2: ifconfig ethX down -> ndo_close -> phy_stop -> just stop
>>> phy state machine.
>>> step 3: plugin the network cable, and autoneg complete, then
>>> LED for link status will be on.
>>> step 4: ethtool ethX --> see the result of "Link detected" is no.
>>>
>> Step 3 and 4 seem to be unrelated to the actual issue.
>> With which MAC + PHY driver did you observe this?
>>
> Thanks Heiner,
> 
> I tested this on HNS3 driver, with two phy, Marvell 88E1512 and RTL8211.
> 
> Step 3 and Step 4 is just to describe that the LED of link shows link up,
> but the port information shows no link.
> 
ethtool refers to the link at MAC level. Therefore default implementation
ethtool_op_get_link just returns the result of netif_carrier_ok().
Also using PHY link status if interface is down doesn't really make sense:
- phylib state machine isn't running, therefore PHY status doesn't get updated
- often MAC drivers shut down parts of the MAC on ndo_close, this typically
  makes the internal MDIO bus unaccessible
So just remove steps 3 and 4. The patch itself is fine with me.

> 
>>> This patch forces phy suspend even phydev->link is off.
>>>
>>> Signed-off-by: Jian Shen <shenjian15@...wei.com>
>>> ---
>>>  drivers/net/phy/phy.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
>>> index f3adea9..0acd5b4 100644
>>> --- a/drivers/net/phy/phy.c
>>> +++ b/drivers/net/phy/phy.c
>>> @@ -911,8 +911,8 @@ void phy_state_machine(struct work_struct *work)
>>>  		if (phydev->link) {
>>>  			phydev->link = 0;
>>>  			phy_link_down(phydev, true);
>>> -			do_suspend = true;
>>>  		}
>>> +		do_suspend = true;
>>>  		break;
>>>  	}
>>>  
>>>
>> Heiner
>>
>>
> 
>