netdev - Re: [PATCH] net: phy: micrel: ksz9031/ksz9131: add cabletest support

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Message-ID: <Yk4/Cm3uuBF7vplL@lunn.ch>
Date:   Thu, 7 Apr 2022 03:31:54 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Marek Vasut <marex@...x.de>
Cc:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH] net: phy: micrel: ksz9031/ksz9131: add cabletest support

> +static int ksz9x31_cable_test_start(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	/* KSZ9131RNX, DS00002841B-page 38, 4.14 LinkMD (R) Cable Diagnostic
> +	 * Prior to running the cable diagnostics, Auto-negotiation should
> +	 * be disabled, full duplex set and the link speed set to 1000Mbps
> +	 * via the Basic Control Register.
> +	 */
> +	ret = phy_modify(phydev, MII_BMCR,
> +			 BMCR_SPEED1000 | BMCR_FULLDPLX |
> +			 BMCR_ANENABLE | BMCR_SPEED100,
> +			 BMCR_SPEED1000 | BMCR_FULLDPLX);
> +	if (ret)
> +		return ret;
> +
> +	/* KSZ9131RNX, DS00002841B-page 38, 4.14 LinkMD (R) Cable Diagnostic
> +	 * The Master-Slave configuration should be set to Slave by writing
> +	 * a value of 0x1000 to the Auto-Negotiation Master Slave Control
> +	 * Register.
> +	 */
> +	return phy_modify(phydev, MII_CTRL1000,
> +			  CTL1000_ENABLE_MASTER | CTL1000_AS_MASTER,
> +			  CTL1000_ENABLE_MASTER);

Did you check if this gets undone when the cable test is
completed? The phy state machine will call phy_init_hw(), but i've no
idea if that is sufficient to reset the master selection.

Otherwise, this looks good.

	   Andrew