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

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Message-ID: <20250429200306.GE1969140@ragnatech.se>
Date: Tue, 29 Apr 2025 22:03:06 +0200
From: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
To: Dimitri Fedrau <dima.fedrau@...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>,
	Gregor Herburger <gregor.herburger@...tq-group.com>,
	Stefan Eichenberger <eichest@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kory Maincent <kory.maincent@...tlin.com>
Subject: Re: [PATCH net-next v3] net: phy: marvell-88q2xxx: Enable
 temperature measurement in probe again

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@...tlin.com>
> Signed-off-by: Dimitri Fedrau <dima.fedrau@...il.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.

That being said I tested this with mv88q211x and the temp sensor and PHY 
keeps working as expected.

Tested-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>

>  
>  	priv->enable_temp = true;
>  
> 
> ---
> base-commit: 0d15a26b247d25cd012134bf8825128fedb15cc9
> change-id: 20250217-marvell-88q2xxx-hwmon-enable-at-probe-2a2666325985
> 
> Best regards,
> -- 
> Dimitri Fedrau <dima.fedrau@...il.com>
> 

-- 
Kind Regards,
Niklas Söderlund