Re: [PATCH net-next v3] net: phy: marvell-88q2xxx: Enable temperature measurement in probe again

[Dimitri Fedrau <dima.fedrau@gmail.com>]

Hi Niklas,

Am Tue, Apr 29, 2025 at 10:03:06PM +0200 schrieb Niklas Söderlund:
> Hi Dimitri,
> 
> Thanks for your work.
> 
> On 2025-04-29 08:54:25 +0200, 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.
> > 
> > Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
> > Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
> > ---
> > Changes in v3:
> > - Remove patch "net: phy: marvell-88q2xxx: Prevent hwmon access with asserted reset"
> >   from series. There will be a separate patch handling this and I'm not
> >   sure if it is going to be accepted. Separating this is necessary
> >   because the temperature reading is somehow odd at the moment, because
> >   the interface has to be brought up for it to work. See:
> >   https://lore.kernel.org/netdev/20250418145800.2420751-1-niklas.soderlund+renesas@ragnatech.se/
> > - Link to v2: https://lore.kernel.org/r/20250220-marvell-88q2xxx-hwmon-enable-at-probe-v2-0-78b2838a62da@gmail.com
> > 
> > Changes in v2:
> > - Add comment in mv88q2xxx_config_init why the temperature sensor is
> >   enabled again (Stefan)
> > - Fix commit message by adding the information why the PHY reset might
> >   be asserted. (Andrew)
> > - Remove fixes tags (Andrew)
> > - Switch to net-next (Andrew)
> > - Return ENETDOWN instead of EIO when PHYs reset is asserted in
> >   mv88q2xxx_hwmon_read (Andrew)
> > - Add check if PHYs reset is asserted in mv88q2xxx_hwmon_write as it was
> >   done in mv88q2xxx_hwmon_read
> > - Link to v1: https://lore.kernel.org/r/20250218-marvell-88q2xxx-hwmon-enable-at-probe-v1-0-999a304c8a11@gmail.com
> > ---
> >  drivers/net/phy/marvell-88q2xxx.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/phy/marvell-88q2xxx.c b/drivers/net/phy/marvell-88q2xxx.c
> > index 5c687164b8e068f3f09e91cd4dd198f24782682e..5d2fbbf332933ffe06f4506058e380fbc7c52921 100644
> > --- a/drivers/net/phy/marvell-88q2xxx.c
> > +++ b/drivers/net/phy/marvell-88q2xxx.c
> > @@ -513,7 +513,10 @@ static int mv88q2xxx_config_init(struct phy_device *phydev)
> >  			return ret;
> >  	}
> >  
> > -	/* Enable temperature sense */
> > +	/* Enable temperature sense again. There might have been a hard reset
> > +	 * of the PHY and in this case the register content is restored to
> > +	 * defaults and we need to enable it again.
> > +	 */
> >  	if (priv->enable_temp) {
> >  		ret = phy_modify_mmd(phydev, MDIO_MMD_PCS,
> >  				     MDIO_MMD_PCS_MV_TEMP_SENSOR2,
> > @@ -765,6 +768,13 @@ static int mv88q2xxx_hwmon_probe(struct phy_device *phydev)
> >  	struct mv88q2xxx_priv *priv = phydev->priv;
> >  	struct device *dev = &phydev->mdio.dev;
> >  	struct device *hwmon;
> > +	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;
> 
> nit: I wonder if it make sens to create a helper function to enable the 
> sensor? My worry being this procedure growing in the future and only 
> being fixed in one location and not the other. It would also reduce code 
> duplication and could be stubbed to be compiled out with the existing 
> IS_ENABLED(CONFIG_HWMON) guard for other hwmon functions.
>

thanks for testing. Wouldn't it then be better to implement HWMON_T_ENABLE
instead ? Add the enablement into mv88q2xxx_hwmon_write and the user is
responsible for enablement of the sensor ?

Best regards,
Dimitri Fedrau