netdev - Re: [PATCH net-next 1/2] net: phy: check for aneg disabled and half duplex in phy_ethtool_set

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Message-ID: <20200510140521.GM1551@shell.armlinux.org.uk>
Date:   Sun, 10 May 2020 15:05:21 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 1/2] net: phy: check for aneg disabled and half
 duplex in phy_ethtool_set_eee

On Sun, May 10, 2020 at 10:11:33AM +0200, Heiner Kallweit wrote:
> EEE requires aneg and full duplex, therefore return EPROTONOSUPPORT
> if aneg is disabled or aneg resulted in a half duplex mode.

I think this is completely wrong.  This is the ethtool configuration
interface for EEE that you're making fail.

Why should you not be able to configure EEE parameters if the link
happens to negotiated a half-duplex?  Why should you not be able to
adjust the EEE advertisment via ethtool if the link has negotiated
half-duplex?

Why should any of this configuration depend on the current state?

Why should we force people to negotiate a FD link before they can
then configure EEE, and then have to perform a renegotiation?

Sorry, but to me this patch seems to be a completely wrong approach,
and I really don't get what problem it is trying to fix.

> 
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
>  drivers/net/phy/phy.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 8c22d02b4..891bb6929 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1110,6 +1110,9 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
>  	if (!phydev->drv)
>  		return -EIO;
>  
> +	if (phydev->autoneg == AUTONEG_DISABLE || phydev->duplex == DUPLEX_HALF)
> +		return -EPROTONOSUPPORT;
> +
>  	/* Get Supported EEE */
>  	cap = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_EEE_ABLE);
>  	if (cap < 0)
> -- 
> 2.26.2
> 
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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