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SubjectRe: [PATCH net] net: phy: Avoid multiple suspends
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On 3/10/20 7:16 AM, Geert Uytterhoeven wrote:
> Hi Florian, David,
>
> On Mon, Feb 24, 2020 at 5:59 AM David Miller <davem@davemloft.net> wrote:
>> From: Florian Fainelli <f.fainelli@gmail.com>
>> Date: Thu, 20 Feb 2020 15:34:53 -0800
>>
>>> It is currently possible for a PHY device to be suspended as part of a
>>> network device driver's suspend call while it is still being attached to
>>> that net_device, either via phy_suspend() or implicitly via phy_stop().
>>>
>>> Later on, when the MDIO bus controller get suspended, we would attempt
>>> to suspend again the PHY because it is still attached to a network
>>> device.
>>>
>>> This is both a waste of time and creates an opportunity for improper
>>> clock/power management bugs to creep in.
>>>
>>> Fixes: 803dd9c77ac3 ("net: phy: avoid suspending twice a PHY")
>>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>>
>> Applied, and queued up for -stable, thanks Florian.
>
> This patch causes a regression on r8a73a4/ape6evm and sh73a0/kzm9g.
> After resume from s2ram, Ethernet no longer works:
>
> PM: suspend exit
> nfs: server aaa.bbb.ccc.ddd not responding, still trying
> ...
>
> Reverting commit 503ba7c6961034ff ("net: phy: Avoid multiple suspends")
> fixes the issue.
>
> On both boards, an SMSC LAN9220 is connected to a power-managed local
> bus.
>
> I added some debug code to check when the clock driving the local bus
> is stopped and started, but I see no difference before/after. Hence I
> suspect the Ethernet chip is no longer reinitialized after resume.

Can you provide a complete log? Do you use the Generic PHY driver or a
specialized one? Do you have a way to dump the registers at the time of
failure and see if BMCR.PDOWN is still set somehow?

Does the following help:

diff --git a/drivers/net/ethernet/smsc/smsc911x.c
b/drivers/net/ethernet/smsc/smsc911x.c
index 49a6a9167af4..df17190c76c0 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -2618,6 +2618,7 @@ static int smsc911x_resume(struct device *dev)
if (netif_running(ndev)) {
netif_device_attach(ndev);
netif_start_queue(ndev);
+ phy_resume(dev->phydev);
}

return 0;
--
Florian
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