linux-kernel - Re: [PATCH] net/phy: Micrel KSZ8061 PHY link failure after cable connect

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Message-ID: <20180619152858.GD26796@lunn.ch>
Date:   Tue, 19 Jun 2018 17:28:58 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     "Onnasch, Alexander (EXT)" <Alexander.Onnasch@...disgyr.com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net/phy: Micrel KSZ8061 PHY link failure after cable
 connect

On Tue, Jun 19, 2018 at 02:23:41PM +0000, Onnasch, Alexander (EXT) wrote:
> Hi Andrew
> thanks for the hint. But actually I cannot confirm - or I don't see it yet. 
> 
> Without having tested, just from the code, the struct phy_driver instance for PHY_ID_KSZ8061 in micrel.c does not have a .write_mmd function assigned, thus phy_write_mmd should evaluate to its else-clause (see below) and not to mdiobus_write (as in phy_write).
> 
> Also the ksz8061_extended_write() function which I have added uses the same principle as already existing HW-specific functions in micrel.c for simular reasons (kszphy_extended_write and ksz9031_extended_write).
> They use phy_write all over the place in that file and never phy_write_mmd - for whatever reason they had.
> Thus I thought it would be a good idea ...

Hi Alexander

Please don't top post. And wrap your lines at around 75 characters 

> 		struct mii_bus *bus = phydev->mdio.bus;
> 		int phy_addr = phydev->mdio.addr;
> 
> 		mutex_lock(&bus->mdio_lock);
> 		mmd_phy_indirect(bus, phy_addr, devad, regnum);
> 
> 		/* Write the data into MMD's selected register */
> 		bus->write(bus, phy_addr, MII_MMD_DATA, val);
> 		mutex_unlock(&bus->mdio_lock);


> > +static int ksz8061_extended_write(struct phy_device *phydev,
> > +				  u8 mode, u32 dev_addr, u32 regnum, u16 val) {
> > +	phy_write(phydev, MII_KSZ8061RN_MMD_CTRL_REG, dev_addr);
> > +	phy_write(phydev, MII_KSZ8061RN_MMD_REGDATA_REG, regnum);
> > +	phy_write(phydev, MII_KSZ8061RN_MMD_CTRL_REG, (mode << 14) | dev_addr);
> > +	return phy_write(phydev, MII_KSZ8061RN_MMD_REGDATA_REG, val); }
> 
> Hi Alexander
> 
> This looks a lot like phy_write_mmd().

Look closely at the two implementations. Look at what
mmd_phy_indirect() does. I _think_ these are identical. So don't add
your own helper, please use the core code.

     Andrew