> -----Original Message----- > From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> > Sent: 2023年3月16日 16:02 > To: Wei Fang <wei.fang@xxxxxxx>; linux-renesas-soc@xxxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; Shenwei Wang <shenwei.wang@xxxxxxx>; Clark > Wang <xiaoning.wang@xxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>; David S. > Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>; > Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; > linux-kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx > Subject: Re: [PATCH net-next 3/4] fec: add FIXME to move 'mac_managed_pm' > to probe > > > > Yes, I will resend the series as RFC with more explanations. > > Because I was able to fix SMSC myself, I'll just describe the procedure > here: > > 1) apply this debug patch: > > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index > 1b2e253fce75..7b79c5979486 100644 > --- a/drivers/net/phy/phy_device.c > +++ b/drivers/net/phy/phy_device.c > @@ -310,6 +310,8 @@ static __maybe_unused int > mdio_bus_phy_suspend(struct device *dev) > if (phydev->mac_managed_pm) > return 0; > > +printk(KERN_INFO "****** MDIO suspend\n"); > + > /* Wakeup interrupts may occur during the system sleep transition when > * the PHY is inaccessible. Set flag to postpone handling until the PHY > * has resumed. Wait for concurrent interrupt handler to complete. > > 2) boot the device without bringing the interface (and thus the PHY) up. > Bringing it down after it was up is not the same! It is important > that it was never up before. > > 3) do a suspend-to-ram/resume cycle > > 4) your log should show the above debug message. If not, I was wrong > > 5) If yes, apply a similar fix to the one I did for the Renesas drivers > in this series > > 6) suspend/resume should not show the debug message anymore > > 7) test for regressions and send out :) > > I hope this was understandable. If not, feel free to ask. > > Happy hacking, > Thank you Wolfram. But I'm not sure whether it's really an issue. The flag " mac_managed_pm" indicates that the MAC driver will take care of suspending/resuming the PHY, that is to say the MAC driver calls phy_stop()/phy_start() in its PM callbacks. If a ethernet interface never brings up, the MAC PM callbacks do nothing and just return 0 directly. So I think it's fine for the MDIO PM to do suspend/resume the PHY unless the MDIO bus can't be accessed.
