netdev - Re: [PATCH 09/19] usbnet: smsc95xx: Connect to phydev

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Date:   Fri, 4 Jan 2019 03:18:14 +0100
From:   Marek Vasut <marex@...x.de>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Nisar Sayed <Nisar.Sayed@...rochip.com>,
        Woojung Huh <Woojung.Huh@...rochip.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH 09/19] usbnet: smsc95xx: Connect to phydev

On 1/3/19 2:22 PM, Andrew Lunn wrote:
> On Thu, Jan 03, 2019 at 02:10:30AM +0100, Marek Vasut wrote:
>> Add code to detect and connect to PHY. The internal PHY of the SMSC95xx
>> is a regular SMSC LAN8700 and the driver only supports the internal PHY,
>> so just use the SMSC PHY driver to configure the PHY. Note that the
>> driver does a lot of extra configuration of the PHY, which is left in
>> to avoid breakage. Some of the extra configuration is sorted out by
>> later patches in this series.
> 
> Hi Marek
> 
> A MAC driver is not expected to touch the PHY at all.

Well, sure, that's not how the SMSC95xx driver is implemented. This
series tries to make that a bit better.

> Please try to
> remove as much of the extra configuration as possible, adding it to
> the LAN8700 PHY driver as needed.

Sure, that's the plan.

> You also have to be careful of locking. phylib takes the phydev lock
> when calling into the PHY driver. Anything the MAC does to the PHY is
> not going to be done with this lock held. So bad things can happen.

I think I can add a patch which grabs the lock in the MDIO accessors
used by the SMSC95xx driver, at least temporarily, until it is fully
migrated to phydev ? Or is there a better option ?

-- 
Best regards,
Marek Vasut