linux-kernel - Re: [PATCH] net: phy: mscc: enable MAC SerDes autonegotiation

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Message-ID: <YhdimdT1qLdGqPAW@shell.armlinux.org.uk>
Date:   Thu, 24 Feb 2022 10:48:57 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Raag Jadav <raagjadav@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Steen Hegelund <steen.hegelund@...rochip.com>,
        Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: mscc: enable MAC SerDes autonegotiation

Sorry for the late comment on this patch.

On Sat, Feb 05, 2022 at 12:14:52PM +0530, Raag Jadav wrote:
> +static int vsc85xx_config_inband_aneg(struct phy_device *phydev, bool enabled)
> +{
> +	int rc;
> +	u16 reg_val = 0;
> +
> +	if (enabled)
> +		reg_val = MSCC_PHY_SERDES_ANEG;
> +
> +	mutex_lock(&phydev->lock);
> +
> +	rc = phy_modify_paged(phydev, MSCC_PHY_PAGE_EXTENDED_3,
> +			      MSCC_PHY_SERDES_PCS_CTRL, MSCC_PHY_SERDES_ANEG,
> +			      reg_val);
> +
> +	mutex_unlock(&phydev->lock);

What is the reason for the locking here?

phy_modify_paged() itself is safe due to the MDIO bus lock, so you
shouldn't need locking around it.

Thanks.

-- 
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