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SubjectRe: [RFC PATCH net] net: phy: fix the issue that netif always links up after resuming
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On 30.11.2018 05:37, Kunihiko Hayashi wrote:
> Hi Heiner Florian,
>
> Thank you for your comments.
>
> On Thu, 29 Nov 2018 16:37:48 -0800 <f.fainelli@gmail.com> wrote:
>
>>
>>
>> On 11/29/2018 2:47 PM, Heiner Kallweit wrote:
>>> On 29.11.2018 09:12, Kunihiko Hayashi wrote:
>>>> Even though the link is down before entering hibernation,
>>>> there is an issue that the network interface always links up after resuming
>>>> from hibernation.
>>>>
>>>> The phydev->state is PHY_READY before enabling the network interface, so
>>>> the link is down. After resuming from hibernation, the phydev->state is
>>>> forcibly set to PHY_UP in mdio_bus_phy_restore(), and the link becomes up.
>>>>
>>>> This patch expects to solve the issue by changing phydev->state to PHY_UP
>>>> only when the link is up.
>>>>
>>>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
>>>> ---
>>>> drivers/net/phy/phy_device.c | 6 ++++--
>>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
>>>> index ab33d17..d5bba0f 100644
>>>> --- a/drivers/net/phy/phy_device.c
>>>> +++ b/drivers/net/phy/phy_device.c
>>>> @@ -309,8 +309,10 @@ static int mdio_bus_phy_restore(struct device *dev)
>>>> return ret;
>>>>
>>>> /* The PHY needs to renegotiate. */
>>>> - phydev->link = 0;
>>>> - phydev->state = PHY_UP;
>>>> + if (phydev->link) {
>>>> + phydev->link = 0;
>>>> + phydev->state = PHY_UP;
>>>> + }
>>>>
>>> Thanks for reporting. I agree that it isn't right to unconditionally set
>>> PHY_UP, because we don't know whether the PHY was started before
>>> hibernation. However I don't think using phydev->link as criteria is
>>> right. Example would be: PHY was started before hibernation, but w/o link.
>>> In this case we want to set PHY_UP to start an aneg, because a cable may
>>> have been plugged in whilst system was sleeping.
>
> Indeed. I didn't consider the case that the PHY was started but a cable was
> unplugged before hibernation.
>
>>> So I think, similar to phy_stop_machine, we should use state >= UP and
>>> state != HALTED as criteria, and also phy_start_machine() would need to
>>> be called only if this criteria is met.
>>>
>>> It may make sense to add a helper for checking whether PHY is in a
>>> started state (>=UP && !=HALTED), because we need this in more than
>>> one place.
>>
>> Agreed, that would make sense.
>
> I agree, too.
> I'll try this in v2 patch that changes the PHY state to PHY_UP and calls
> phy_start_machine(), only when the PHY was started before hibernation.
> If I understand correctly, it will be like that:
>
> phydev->link = 0;
Even this may go into the if clause. If PHY isn't started then
phydev->link should be 0 anyway.

> if (phy_is_started(phydev)) {
> phydev->state = PHY_UP;
> phy_start_machine(phydev);
> }
>
Yes, this is what was meant. Thanks.

> Thank you,
>
> ---
> Best Regards,
> Kunihiko Hayashi
>
>
>

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