netdev - Re: [PATCH net-next 6/7] net: phy: smsc: add edpd tunable support

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Date:   Sun, 2 Apr 2023 14:08:53 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 6/7] net: phy: smsc: add edpd tunable support

On Sun, Apr 02, 2023 at 11:47:34AM +0200, Heiner Kallweit wrote:
> This adds support for the EDPD PHY tunable.
> Per default EDPD is disabled in interrupt mode, the tunable can be used
> to override this, e.g. if the link partner doesn't use EDPD.
> The interval to check for energy can be chosen between 1000ms and
> 2000ms. Note that this value consists of the 1000ms phylib interval
> for state machine runs plus the time to wait for energy being detected.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
>  drivers/net/phy/smsc.c  | 82 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/smscphy.h |  4 ++
>  2 files changed, 86 insertions(+)
> 
> diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
> index 0cd433f01..cca5bf46f 100644
> --- a/drivers/net/phy/smsc.c
> +++ b/drivers/net/phy/smsc.c
> @@ -34,6 +34,8 @@
>  #define SPECIAL_CTRL_STS_AMDIX_STATE_	0x2000
>  
>  #define EDPD_MAX_WAIT_DFLT		640

nit: Maybe this could be EDPD_MAX_WAIT_DFLT_MS for consistency
     with PHY_STATE_MACH_MS.

> +/* interval between phylib state machine runs in ms */
> +#define PHY_STATE_MACH_MS		1000
>  
>  struct smsc_hw_stat {
>  	const char *string;
> @@ -295,6 +297,86 @@ static void smsc_get_stats(struct phy_device *phydev,
>  		data[i] = smsc_get_stat(phydev, i);
>  }
>  
> +static int smsc_phy_get_edpd(struct phy_device *phydev, u16 *edpd)
> +{
> +	struct smsc_phy_priv *priv = phydev->priv;
> +
> +	if (!priv)
> +		return -EOPNOTSUPP;
> +
> +	if (!priv->edpd_enable)
> +		*edpd = ETHTOOL_PHY_EDPD_DISABLE;
> +	else if (!priv->edpd_max_wait_ms)
> +		*edpd = ETHTOOL_PHY_EDPD_NO_TX;
> +	else
> +		*edpd = PHY_STATE_MACH_MS + priv->edpd_max_wait_ms;
> +
> +	return 0;
> +}
> +
> +static int smsc_phy_set_edpd(struct phy_device *phydev, u16 edpd)
> +{
> +	struct smsc_phy_priv *priv = phydev->priv;
> +	int ret;
> +
> +	if (!priv)
> +		return -EOPNOTSUPP;
> +
> +	mutex_lock(&phydev->lock);

I am a little confused by this as by my reasoning this code is called via
the first arm of the following in set_phy_tunable(), and phydev->lock is
already held.

        if (phy_drv_tunable) {
                mutex_lock(&phydev->lock);
                ret = phydev->drv->set_tunable(phydev, &tuna, data);
                mutex_unlock(&phydev->lock);
        } else {
                ret = dev->ethtool_ops->set_phy_tunable(dev, &tuna, data);
        }

> +
> +	switch (edpd) {
> +	case ETHTOOL_PHY_EDPD_DISABLE:
> +		priv->edpd_enable = false;
> +		break;
> +	case ETHTOOL_PHY_EDPD_NO_TX:
> +		priv->edpd_enable = true;
> +		priv->edpd_max_wait_ms = 0;
> +		break;
> +	case ETHTOOL_PHY_EDPD_DFLT_TX_MSECS:
> +		edpd = PHY_STATE_MACH_MS + EDPD_MAX_WAIT_DFLT;
> +		fallthrough;
> +	default:
> +		if (phydev->irq != PHY_POLL)
> +			return -EOPNOTSUPP;

This returns without releasing phydev->lock.
Is that intended?

> +		if (edpd < PHY_STATE_MACH_MS || edpd > PHY_STATE_MACH_MS + 1000)
> +			return -EINVAL;

Ditto.

> +		priv->edpd_enable = true;
> +		priv->edpd_max_wait_ms = edpd - PHY_STATE_MACH_MS;
> +	}
> +
> +	priv->edpd_mode_set_by_user = true;
> +
> +	ret = smsc_phy_config_edpd(phydev);
> +
> +	mutex_unlock(&phydev->lock);
> +
> +	return ret;
> +}
> +
> +int smsc_phy_get_tunable(struct phy_device *phydev,
> +			 struct ethtool_tunable *tuna, void *data)
> +{
> +	switch (tuna->id) {
> +	case ETHTOOL_PHY_EDPD:
> +		return smsc_phy_get_edpd(phydev, data);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(smsc_phy_get_tunable);
> +
> +int smsc_phy_set_tunable(struct phy_device *phydev,
> +			 struct ethtool_tunable *tuna, const void *data)
> +{
> +	switch (tuna->id) {
> +	case ETHTOOL_PHY_EDPD:
> +		return smsc_phy_set_edpd(phydev, *(u16 *)data);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(smsc_phy_set_tunable);
> +
>  int smsc_phy_probe(struct phy_device *phydev)
>  {
>  	struct device *dev = &phydev->mdio.dev;
> diff --git a/include/linux/smscphy.h b/include/linux/smscphy.h
> index 80f37c1db..e1c886277 100644
> --- a/include/linux/smscphy.h
> +++ b/include/linux/smscphy.h
> @@ -32,6 +32,10 @@ int smsc_phy_config_intr(struct phy_device *phydev);
>  irqreturn_t smsc_phy_handle_interrupt(struct phy_device *phydev);
>  int smsc_phy_config_init(struct phy_device *phydev);
>  int lan87xx_read_status(struct phy_device *phydev);
> +int smsc_phy_get_tunable(struct phy_device *phydev,
> +			 struct ethtool_tunable *tuna, void *data);
> +int smsc_phy_set_tunable(struct phy_device *phydev,
> +			 struct ethtool_tunable *tuna, const void *data);
>  int smsc_phy_probe(struct phy_device *phydev);
>  
>  #endif /* __LINUX_SMSCPHY_H__ */
> -- 
> 2.40.0
> 
>