linux-kernel - Re: [PATCH] net: phy: at803x: stop switching phy delay config needlessly

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Date:   Fri, 09 Aug 2019 11:00:05 +0100
From:   André Draszik <git@...red.net>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     lkml <linux-kernel@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: phy: at803x: stop switching phy delay config
 needlessly

Hi Vladimir,

On Fri, 2019-08-09 at 12:43 +0300, Vladimir Oltean wrote:
> Hi Andre,
> 
> On Fri, 9 Aug 2019 at 03:58, André Draszik <git@...red.net> wrote:
> > This driver does a funny dance disabling and re-enabling
> > RX and/or TX delays. In any of the RGMII-ID modes, it first
> > disables the delays, just to re-enable them again right
> > away. This looks like a needless exercise.
> > 
> > Just enable the respective delays when in any of the
> > relevant 'id' modes, and disable them otherwise.
> > 
> > Also, remove comments which don't add anything that can't be
> > seen by looking at the code.
> > 
> > Signed-off-by: André Draszik <git@...red.net>
> > CC: Andrew Lunn <andrew@...n.ch>
> > CC: Florian Fainelli <f.fainelli@...il.com>
> > CC: Heiner Kallweit <hkallweit1@...il.com>
> > CC: "David S. Miller" <davem@...emloft.net>
> > CC: netdev@...r.kernel.org
> > ---
> 
> Is there any particular problem you're facing? Does this make any difference?

This is a clean-up, reducing the number of lines and if statements
by removing unnecessary code paths and comments.


Cheers,
Andre'


> 
> >  drivers/net/phy/at803x.c | 26 ++++++--------------------
> >  1 file changed, 6 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> > index 222ccd9ecfce..2ab51f552e92 100644
> > --- a/drivers/net/phy/at803x.c
> > +++ b/drivers/net/phy/at803x.c
> > @@ -257,35 +257,21 @@ static int at803x_config_init(struct phy_device *phydev)
> >          *   after HW reset: RX delay enabled and TX delay disabled
> >          *   after SW reset: RX delay enabled, while TX delay retains the
> >          *   value before reset.
> > -        *
> > -        * So let's first disable the RX and TX delays in PHY and enable
> > -        * them based on the mode selected (this also takes care of RGMII
> > -        * mode where we expect delays to be disabled)
> >          */
> > -
> > -       ret = at803x_disable_rx_delay(phydev);
> > -       if (ret < 0)
> > -               return ret;
> > -       ret = at803x_disable_tx_delay(phydev);
> > -       if (ret < 0)
> > -               return ret;
> > -
> >         if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> >             phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
> > -               /* If RGMII_ID or RGMII_RXID are specified enable RX delay,
> > -                * otherwise keep it disabled
> > -                */
> >                 ret = at803x_enable_rx_delay(phydev);
> > -               if (ret < 0)
> > -                       return ret;
> > +       } else {
> > +               ret = at803x_disable_rx_delay(phydev);
> >         }
> > +       if (ret < 0)
> > +               return ret;
> > 
> >         if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
> >             phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
> > -               /* If RGMII_ID or RGMII_TXID are specified enable TX delay,
> > -                * otherwise keep it disabled
> > -                */
> >                 ret = at803x_enable_tx_delay(phydev);
> > +       } else {
> > +               ret = at803x_disable_tx_delay(phydev);
> >         }
> > 
> >         return ret;
> > --
> > 2.20.1
> > 
> 
> Regards,
> -Vladimir