Re: [PATCH RFC v1 4/7] net: phy: suspend unused PHYs on mdio_bus in late_initcall

[Florian Fainelli]

2013/11/20 Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>:
> Since phy_attach ensures PHYs are resumed, we can now suspend all
> PHYs that have no attached netdev after initcalls.

I do like the idea, but I think you might want to make sure that the
MDIO bus suspend policy was set to "auto" (which is the default afair)
not to expose unexpected behavior.

>
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> ---
> Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  drivers/net/phy/mdio_bus.c |   27 +++++++++++++++++++++++++++
>  1 files changed, 27 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 5617876..10eba58 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -320,6 +320,33 @@ static int mdio_bus_match(struct device *dev, struct device_driver *drv)
>                 (phydev->phy_id & phydrv->phy_id_mask));
>  }
>
> +static int mdio_bus_suspend_unused(struct device *busdev, void *data)
> +{
> +       struct mii_bus *bus = to_mii_bus(busdev);
> +       struct phy_device *phydev;
> +       struct phy_driver *phydrv;
> +       int i;
> +
> +       for (i = 0; i < PHY_MAX_ADDR; i++) {
> +               if (!bus->phy_map[i])
> +                       continue;
> +
> +               phydev = to_phy_device(&bus->phy_map[i]->dev);
> +               phydrv = to_phy_driver(phydev->dev.driver);
> +               if (!phydev->attached_dev && phydrv && phydrv->suspend)
> +                       phy_suspend(phydev);
> +       }
> +
> +       return 0;

You might want to reuse mdio_bus_phy_may_suspend() here to have a
central place checking for phydev->attached_dev and phydrv->suspend
just in case we need to add more callbacks in the future or implicit
PHY state machine hooks. That might also take care of my concern
expressed above.

> +}
> +
> +static int mdio_bus_class_suspend_unused(void)
> +{
> +       return class_for_each_device(&mdio_bus_class, NULL, NULL,
> +                                    mdio_bus_suspend_unused);
> +}
> +late_initcall_sync(mdio_bus_class_suspend_unused);
> +
>  #ifdef CONFIG_PM
>
>  static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
> --
> 1.7.2.5
>
>
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-- 
Florian
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