linux-kernel - 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 12:04:04 +0100
From:   Christian Marangi <ansuelsmth@...il.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
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 10:57:28AM +0000, Russell King (Oracle) wrote:
> 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.
>

Much cleaner thanks for the hint!

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