linux-kernel - Re: [PATCH v2 2/3] net: ethernet: fec: use phydev from struct net

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Message-ID: <572FC20A.5030805@gmail.com>
Date:	Mon, 09 May 2016 00:47:38 +0200
From:	Philippe Reynes <tremyfr@...il.com>
To:	Ben Hutchings <ben@...adent.org.uk>
CC:	fugang.duan@....com, davem@...emloft.net, kan.liang@...el.com,
	decot@...glers.com, aduyck@...antis.com, jiri@...lanox.com,
	jacob.e.keller@...el.com, tom@...bertland.com, andrew@...n.ch,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] net: ethernet: fec: use phydev from struct net_device

On 09/05/16 00:22, Ben Hutchings wrote:
> On Sun, 2016-05-08 at 23:44 +0200, Philippe Reynes wrote:
>> The private structure contain a pointer to phydev, but the structure
>> net_device already contain such pointer. So we can remove the pointer
>> phydev in the private structure, and update the driver to use the one
>> contained in struct net_device.
>
> But there is no central code that updates the pointer, so:

The function phy_attach_direct and phy_detach update the pointer
phydev in the struct net_device.

>
> [...]
>> @@ -1928,7 +1926,6 @@ static int fec_enet_mii_probe(struct net_device *ndev)
>>
>>   	phy_dev->advertising = phy_dev->supported;
>>
>> -	fep->phy_dev = phy_dev;
>
> you need to assign ndev->phydev here

The function fec_enet_mii_probe call of_phy_connect,
which call phy_connect_direct, which call phy_attach_direct.
This last function update the pointer phydev of struct net_device.

> [...]
>> @@ -2875,8 +2869,7 @@ fec_enet_close(struct net_device *ndev)
>>   		fec_stop(ndev);
>>   	}
>>
>> -	phy_disconnect(fep->phy_dev);
>> -	fep->phy_dev = NULL;
>> +	phy_disconnect(ndev->phydev);
> [...]
>
> and you need to set it to NULL here.

The function fec_enet_close call phy_disconnect, which call phy_detach.
This last function set the pointer phydev in the struct net_device to NULL.


So from my understanding, those two lines aren't usefull.
May you confirm that I'm on the right way please ?

  
> Ben.
>

Philippe