netdev - Re: [net-next PATCH 08/14] net: phy: at803x: drop specific PHY id check from cable test functions

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Date: Wed, 29 Nov 2023 10:57:28 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Andy Gross <agross@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [net-next PATCH 08/14] net: phy: at803x: drop specific PHY id
 check from cable test functions

On Wed, Nov 29, 2023 at 10:47:18AM +0100, Christian Marangi wrote:
> On Wed, Nov 29, 2023 at 09:38:39AM +0000, Russell King (Oracle) wrote:
> > On Wed, Nov 29, 2023 at 03:12:13AM +0100, Christian Marangi wrote:
> > > @@ -1310,10 +1302,6 @@ static int at803x_cable_test_start(struct phy_device *phydev)
> > >  	 */
> > >  	phy_write(phydev, MII_BMCR, BMCR_ANENABLE);
> > >  	phy_write(phydev, MII_ADVERTISE, ADVERTISE_CSMA);
> > > -	if (phydev->phy_id != ATH9331_PHY_ID &&
> > > -	    phydev->phy_id != ATH8032_PHY_ID &&
> > > -	    phydev->phy_id != QCA9561_PHY_ID)
> > > -		phy_write(phydev, MII_CTRL1000, 0);
> > ...
> > > +static int at8031_cable_test_start(struct phy_device *phydev)
> > > +{
> > > +	at803x_cable_test_start(phydev);
> > > +	phy_write(phydev, MII_CTRL1000, 0);
> > 
> > I don't think this is a safe change - same reasons as given on a
> > previous patch. You can't randomly reorder register writes like this.
> >
> 
> Actually for this the order is keeped. Generic function is called and
> for at8031 MII_CTRL1000 is called on top of that.

Okay, but I don't like it. I would prefer this to be:

static void at803x_cable_test_autoneg(struct phy_device *phydev)
{
	phy_write(phydev, MII_BMCR, BMCR_ANENABLE);
	phy_write(phydev, MII_ADVERTISE, ADVERTISE_CSMA);
}

static int at803x_cable_test_start(struct phy_device *phydev)
{
	at803x_cable_test_autoneg(phydev);
	return 0;
}

static int at8031_cable_test_start(struct phy_device *phydev)
{
	at803x_cable_test_autoneg(phydev);
	phy_write(phydev, MII_CTRL1000, 0);
	return 0;
}

which makes it more explicit what is going on here. Also a comment
above the function stating that it's for AR8031 _and_ AR8035 would
be useful.

-- 
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