netdev - Re: [PATCH RFC 12/18] net: dsa: mt7530: Call phylib for set_eee and get

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Date:   Fri, 17 Feb 2023 11:48:01 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev <netdev@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Doug Berger <opendmb@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Wei Fang <wei.fang@....com>,
        Shenwei Wang <shenwei.wang@....com>,
        Clark Wang <xiaoning.wang@....com>,
        NXP Linux Team <linux-imx@....com>,
        UNGLinuxDriver@...rochip.com, Byungho An <bh74.an@...sung.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Woojung Huh <woojung.huh@...rochip.com>,
        Oleksij Rempel <linux@...pel-privat.de>
Subject: Re: [PATCH RFC 12/18] net: dsa: mt7530: Call phylib for set_eee and
 get_eee

On Fri, Feb 17, 2023 at 04:42:24AM +0100, Andrew Lunn wrote:
> phylib should be called in order to manage the EEE settings in the
> PHY, and to return EEE status such are supported link modes, and what
> the link peer supports.
> 
> Signed-off-by: Andrew Lunn <andrew@...n.ch>
> ---
>  drivers/net/dsa/mt7530.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 214450378978..a472353f14f8 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -3124,10 +3124,13 @@ static int mt753x_get_mac_eee(struct dsa_switch *ds, int port,
>  {
>  	struct mt7530_priv *priv = ds->priv;
>  	u32 eeecr = mt7530_read(priv, MT7530_PMEEECR_P(port));
> +	struct dsa_port *dp = dsa_to_port(ds, port);
>  
>  	e->tx_lpi_enabled = !(eeecr & LPI_MODE_EN);
>  	e->tx_lpi_timer = GET_LPI_THRESH(eeecr);
>  
> +	if (dp->slave->phydev)
> +		return phy_ethtool_get_eee(dp->slave->phydev, e);

Given that DSA makes use of phylink, is there a reason why we can't use
the phylink wrappers here (which may allow for future EEE improvements,
e.g. moving the gating of EEE with the TX LPI enable) ?

> @@ -3146,6 +3150,8 @@ static int mt753x_set_mac_eee(struct dsa_switch *ds, int port,
>  		set |= LPI_MODE_EN;
>  	mt7530_rmw(priv, MT7530_PMEEECR_P(port), mask, set);
>  
> +	if (dp->slave->phydev)
> +		return phy_ethtool_set_eee(dp->slave->phydev, e);
>  	return 0;


Is this the correct place to do the set_eee operation - I mean, the
register state has been altered (and it looks like it may enable LPI
irrespective of the negotiated state) but what concerns me is that
phy_ethtool_set_eee() can fail, and we return failure to userspace
yet we've modified register state.

-- 
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