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 12:43:47 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Heiner Kallweit <hkallweit1@...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

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?

>  
> -	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?

> -
>  	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);
> 


-- 
Florian