netdev - Re: [PATCH 1/2] net: phy: marvell-88q2xxx: Enable temperature measurement in probe again

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Message-ID: <20250220053223.GA3914@debian>
Date: Thu, 20 Feb 2025 06:32:23 +0100
From: Dimitri Fedrau <dima.fedrau@...il.com>
To: Stefan Eichenberger <eichest@...il.com>
Cc: Andrew Lunn <andrew@...n.ch>, 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>,
	Niklas Söderlund <niklas.soderlund+renesas@...natech.se>,
	Gregor Herburger <gregor.herburger@...tq-group.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] net: phy: marvell-88q2xxx: Enable temperature
 measurement in probe again

Am Wed, Feb 19, 2025 at 06:25:47PM +0100 schrieb Stefan Eichenberger:
> Hi Dimitri,
> 
> On Wed, Feb 19, 2025 at 11:46:47AM +0100, Dimitri Fedrau wrote:
> > Hi Stefan,
> > 
> > thanks for reviewing.
> > 
> > Am Wed, Feb 19, 2025 at 07:16:58AM +0100 schrieb Stefan Eichenberger:
> > > Hi Dimitri,
> > > 
> > > On Tue, Feb 18, 2025 at 07:33:09PM +0100, Dimitri Fedrau wrote:
> > > > Enabling of the temperature sensor was moved from mv88q2xxx_hwmon_probe to
> > > > mv88q222x_config_init with the consequence that the sensor is only
> > > > usable when the PHY is configured. Enable the sensor in
> > > > mv88q2xxx_hwmon_probe as well to fix this.
> > > > 
> > > > Fixes: a197004cf3c2 ("net: phy: marvell-88q2xxx: Fix temperature measurement with reset-gpios")
> > > > Signed-off-by: Dimitri Fedrau <dima.fedrau@...il.com>
> > > > ---
> > > >  drivers/net/phy/marvell-88q2xxx.c | 7 +++++++
> > > >  1 file changed, 7 insertions(+)
> > > > 
> > > > diff --git a/drivers/net/phy/marvell-88q2xxx.c b/drivers/net/phy/marvell-88q2xxx.c
> > > > index a3996471a1c9a5d4060d5d19ce44aa70e902a83f..30d71bfc365597d77c34c48f05390db9d63c4af4 100644
> > > > --- a/drivers/net/phy/marvell-88q2xxx.c
> > > > +++ b/drivers/net/phy/marvell-88q2xxx.c
> > > > @@ -718,6 +718,13 @@ static int mv88q2xxx_hwmon_probe(struct phy_device *phydev)
> > > >  	struct device *dev = &phydev->mdio.dev;
> > > >  	struct device *hwmon;
> > > >  	char *hwmon_name;
> > > > +	int ret;
> > > > +
> > > > +	/* Enable temperature sense */
> > > > +	ret = phy_modify_mmd(phydev, MDIO_MMD_PCS, MDIO_MMD_PCS_MV_TEMP_SENSOR2,
> > > > +			     MDIO_MMD_PCS_MV_TEMP_SENSOR2_DIS_MASK, 0);
> > > > +	if (ret < 0)
> > > > +		return ret;
> > > >  
> > > >  	priv->enable_temp = true;
> > > >  	hwmon_name = devm_hwmon_sanitize_name(dev, dev_name(dev));
> > > 
> > > Is it necessary to have it enabled in probe and in config? Is that
> > > because of the soft reset? Can it happen that the phy is reset but
> > > config is not called, then we would end up in the same situation right?
> > >
> > Even if the phy is not configured yet, it is probed and the PHYs hard reset
> > is deasserted, so I can read the temperature. I think the situation you
> > mean is when the PHY is brought up and down again. In this case the hard
> > reset of the PHY is asserted and I can't read the temperature. That's
> > the second patch of the series that fixes this issue.
> 
> Okay I see, thanks for the explaination. So the code in
> mv88q222x_config_init is required after a hard reset of the phy. I was
> just thinking, if we could avoid the duplication but I guess both
> enables are required. Could you maybe add a comment why we need to have
> it enabled in both places?
>
Will add the comment.