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

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Date:   Fri, 9 Aug 2019 12:43:01 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     André Draszik <git@...red.net>
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 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?

>  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