netdev - RE: [PATCH net] r8169: fix rtl8168h wol fail

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Date:   Fri, 6 Jan 2023 06:53:12 +0000
From:   Hau <hau@...ltek.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        nic_swsd <nic_swsd@...ltek.com>
Subject: RE: [PATCH net] r8169: fix rtl8168h wol fail

> > > rtl8168h has an application that it will connect to rtl8211fs
> > > through mdi interface. And rtl8211fs will connect to fiber through serdes
> interface.
> > > In this application, rtl8168h revision id will be set to 0x2a.
> > >
> > > Because rtl8211fs's firmware will set link capability to 100M and
> > > GIGA when link is from off to on. So when system suspend and wol is
> > > enabled, rtl8168h will speed down to 100M (because rtl8211fs
> > > advertise 100M and GIGA to rtl8168h). If the link speed between
> rtl81211fs and fiber is GIGA.
> > > The link speed between rtl8168h and fiber will mismatch. That will
> > > cause wol fail.
> > >
> > > In this patch, if rtl8168h is in this kind of application, driver
> > > will not speed down phy when wol is enabled.
> > >
> > I think the patch title is inappropriate because WoL works normally on
> > RTL8168h in the standard setup.
> > What you add isn't a fix but a workaround for a firmware bug in RTL8211FS.
> > As mentioned in a previous review comment: if speed on fibre side is
> > 1Gbps then RTL8211FS shouldn't advertise 100Mbps on MDI/UTP side.
> > Last but not least the user can still use e.g. ethtool to change the
> > speed to 100Mbps thus breaking the link.
> 
> I agree with Heiner here. I assume you cannot fix the firmware?
> 
> So can we detect the broken firmware and correctly set
> phydev->advertising? That will fix WoL and should prevent the user
> from using ethtool to select a slower speed.
> 
It is a rtl8211fs's firmware bug. Because in this application it will support both 100M and GIGA
fiber module, so it cannot just set phydev->advertising to 100M or GIGA. We  may need to 
use bit-bang MDIO to detect fiber link speed and set phydev->advertising properly. But it will
let this patch become more complicated.

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