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

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Date:   Sun, 2 Apr 2023 15:52:36 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Simon Horman <simon.horman@...igine.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 02.04.2023 14:08, Simon Horman wrote:
> 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.
> 
Yes, this would be better.

>> +/* 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.
> 

You're right of course. So we can remove the locking in the driver.

>         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
>>
>>