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

From: [email-masked] (Sebastian Hesselbarth)
Date: Wed, 20 Nov 2013 22:05:07 +0100

On 11/20/2013 09:58 PM, Florian Fainelli wrote:
> 2013/11/20 Sebastian Hesselbarth <[email-masked]>:
>> 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.

Ok, TBH I haven't looked through all of phy internals. If we are fine
with the overall approach, I could use some guidance in the individual
patches and policies.

>>
>> Signed-off-by: Sebastian Hesselbarth <[email-masked]>
>> ---
>> Cc: David S. Miller <[email-masked]>
>> Cc: netdev at vger.kernel.org
>> Cc: linux-arm-kernel at lists.infradead.org
>> Cc: linux-kernel at vger.kernel.org
>> ---
>>   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.

Unfortunately, mdio_bus_phy_may_suspend() doesn't help here. It will
correctly tell that unconnected PHYs may_suspend but also that PHYs
connected to PM aware drivers may_suspend.

I tried it and it will also suspend the PHY taken by mv643xx_eth.

But actually, as phy_suspend/resume check for phydrv->suspend
themselves, we can just call it on !phydev->attached_dev and remove
the additional checks.

>> +}
>> +
>> +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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>
>
>