netdev - Re: [PATCH net-next 2/2] net: phy: improve checks for when to suspend the PHY

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Date:   Wed, 23 May 2018 22:05:54 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 2/2] net: phy: improve checks for when to suspend
 the PHY

Am 23.05.2018 um 21:43 schrieb Florian Fainelli:
> On 05/23/2018 12:31 PM, Heiner Kallweit wrote:
>> If the parent of the MDIO bus is runtime-suspended, we may not be able
>> to access the MDIO bus. Therefore add a check for this situation.
>>
>> So far phy_suspend() only checks for WoL being enabled, other checks
>> are in mdio_bus_phy_may_suspend(). Improve this and move all checks
>> to a new function phy_may_suspend() and call it from phy_suspend().
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  drivers/net/phy/phy_device.c | 33 +++++++++++++++++++++------------
>>  1 file changed, 21 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
>> index 1662781fb..e0a71e3e5 100644
>> --- a/drivers/net/phy/phy_device.c
>> +++ b/drivers/net/phy/phy_device.c
>> @@ -35,6 +35,7 @@
>>  #include <linux/io.h>
>>  #include <linux/uaccess.h>
>>  #include <linux/of.h>
>> +#include <linux/pm_runtime.h>
>>  
>>  #include <asm/irq.h>
>>  
>> @@ -75,14 +76,27 @@ extern struct phy_driver genphy_10g_driver;
>>  static LIST_HEAD(phy_fixup_list);
>>  static DEFINE_MUTEX(phy_fixup_lock);
>>  
>> -#ifdef CONFIG_PM
>> -static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>> +static bool phy_may_suspend(struct phy_device *phydev)
>>  {
>>  	struct device_driver *drv = phydev->mdio.dev.driver;
>>  	struct phy_driver *phydrv = to_phy_driver(drv);
>>  	struct net_device *netdev = phydev->attached_dev;
>> +	struct device *mdio_bus_parent = phydev->mdio.bus->parent;
>> +	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
>> +
>> +	if (phydev->suspended || !drv || !phydrv->suspend)
>> +		return false;
>> +
>> +	/* If the device has WOL enabled, we cannot suspend the PHY */
>> +	phy_ethtool_get_wol(phydev, &wol);
>> +	if (wol.wolopts)
>> +		return false;
> 
> phy_ethtool_get_wol() can created MDIO bus accesses so should not this
> be moved after the check for the MDIO bus being runtime suspended?
> 
Good point. Yes, the WoL check needs to be moved.

>>  
>> -	if (!drv || !phydrv->suspend)
>> +	/* If the parent of the MDIO bus is runtime-suspended, the MDIO bus may
>> +	 * not be accessible and we expect the parent to suspend all devices
>> +	 * on the MDIO bus when it suspends.
>> +	 */
>> +	if (mdio_bus_parent && pm_runtime_suspended(mdio_bus_parent))
>>  		return false;
>>  
>>  	/* PHY not attached? May suspend if the PHY has not already been
>> @@ -91,7 +105,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>>  	 * MDIO bus driver and clock gated at this point.
>>  	 */
>>  	if (!netdev)
>> -		return !phydev->suspended;
>> +		return true;
>>  
>>  	/* Don't suspend PHY if the attached netdev parent may wakeup.
>>  	 * The parent may point to a PCI device, as in tg3 driver.
>> @@ -109,6 +123,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>>  	return true;
>>  }
>>  
>> +#ifdef CONFIG_PM
>>  static int mdio_bus_phy_suspend(struct device *dev)
>>  {
>>  	struct phy_device *phydev = to_phy_device(dev);
>> @@ -121,9 +136,6 @@ static int mdio_bus_phy_suspend(struct device *dev)
>>  	if (phydev->attached_dev && phydev->adjust_link)
>>  		phy_stop_machine(phydev);
>>  
>> -	if (!mdio_bus_phy_may_suspend(phydev))
>> -		return 0;
> 
> Hummm why is it okay to drop that one?
> 
All checks in mdio_bus_phy_may_suspend() have been moved to
phy_may_suspend() which is called from phy_suspend()
directly now.

>> -
>>  	return phy_suspend(phydev);
>>  }
>>  
>> @@ -1162,13 +1174,10 @@ EXPORT_SYMBOL(phy_detach);
>>  int phy_suspend(struct phy_device *phydev)
>>  {
>>  	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
>> -	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
>>  	int ret = 0;
>>  
>> -	/* If the device has WOL enabled, we cannot suspend the PHY */
>> -	phy_ethtool_get_wol(phydev, &wol);
>> -	if (wol.wolopts)
>> -		return -EBUSY;
>> +	if (!phy_may_suspend(phydev))
>> +		return 0;
>>  
>>  	if (phydev->drv && phydrv->suspend)
>>  		ret = phydrv->suspend(phydev);
>>
> 
>