linux-kernel - Re: [PATCH net] net: phy: realtek: clear status if link is down

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Message-ID: <7dd12859-dd20-4ce1-a877-4c93b335b911@lunn.ch>
Date: Wed, 15 Jan 2025 03:50:33 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Daniel Golle <daniel@...rotopia.org>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: phy: realtek: clear status if link is down

On Wed, Jan 15, 2025 at 12:46:11AM +0000, Daniel Golle wrote:
> Clear speed, duplex and master/slave status in case the link is down
> to avoid reporting bogus link(-partner) properties.
> 
> Fixes: 5cb409b3960e ("net: phy: realtek: clear 1000Base-T link partner advertisement")
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>  drivers/net/phy/realtek.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
> index f65d7f1f348e..3f0e03e2abce 100644
> --- a/drivers/net/phy/realtek.c
> +++ b/drivers/net/phy/realtek.c
> @@ -720,8 +720,12 @@ static int rtlgen_read_status(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (!phydev->link)
> +	if (!phydev->link) {
> +		phydev->duplex = DUPLEX_UNKNOWN;
> +		phydev->master_slave_state = MASTER_SLAVE_STATE_UNKNOWN;
> +		phydev->speed = SPEED_UNKNOWN;
>  		return 0;
> +	}
>  

I must be missing something here...


rtlgen_read_status() first calls genphy_read_status(phydev);


int genphy_read_status(struct phy_device *phydev)
{
	int err, old_link = phydev->link;

	/* Update the link, but return if there was an error */
	err = genphy_update_link(phydev);
	if (err)
		return err;

	/* why bother the PHY if nothing can have changed */
	if (phydev->autoneg == AUTONEG_ENABLE && old_link && phydev->link)
		return 0;

	phydev->master_slave_get = MASTER_SLAVE_CFG_UNSUPPORTED;
	phydev->master_slave_state = MASTER_SLAVE_STATE_UNSUPPORTED;
	phydev->speed = SPEED_UNKNOWN;
	phydev->duplex = DUPLEX_UNKNOWN;
	phydev->pause = 0;
	phydev->asym_pause = 0;

Why is that not sufficient ?

>  	val = phy_read_paged(phydev, 0xa43, 0x12);
>  	if (val < 0)
> @@ -1028,11 +1032,11 @@ static int rtl822x_c45_read_status(struct phy_device *phydev)
>  		return ret;
>  
>  	if (phydev->autoneg == AUTONEG_DISABLE ||
> -	    !genphy_c45_aneg_done(phydev))
> +	    !genphy_c45_aneg_done(phydev) ||
> +	    !phydev->link) {
>  		mii_stat1000_mod_linkmode_lpa_t(phydev->lp_advertising, 0);
> -
> -	/* Vendor register as C45 has no standardized support for 1000BaseT */
> -	if (phydev->autoneg == AUTONEG_ENABLE) {
> +	} else {
> +		/* Vendor register as C45 has no standardized support for 1000BaseT */
>  		val = phy_read_mmd(phydev, MDIO_MMD_VEND2,
>  				   RTL822X_VND2_GANLPAR);
>  		if (val < 0)
> @@ -1041,8 +1045,12 @@ static int rtl822x_c45_read_status(struct phy_device *phydev)
>  		mii_stat1000_mod_linkmode_lpa_t(phydev->lp_advertising, val);
>  	}
>  
> -	if (!phydev->link)
> +	if (!phydev->link) {
> +		phydev->duplex = DUPLEX_UNKNOWN;
> +		phydev->master_slave_state = MASTER_SLAVE_STATE_UNKNOWN;
> +		phydev->speed = SPEED_UNKNOWN;
>  		return 0;
> +	}


rtl822x_c45_read_status() calls genphy_c45_read_link() which again
clears state from phydev.

	Andrew