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

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Message-ID: <34af6a17f84f4720b13b8b7c61202903@realtek.com>
Date:   Wed, 18 Jan 2023 16:57:11 +0000
From:   Hau <hau@...ltek.com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        nic_swsd <nic_swsd@...ltek.com>
Subject: RE: [PATCH net] r8169: fix rtl8168h wol fail

> On 16.01.2023 18:04, Hau wrote:
> >> On 13.01.2023 17:36, Andrew Lunn wrote:
> >>> On Fri, Jan 13, 2023 at 04:23:45PM +0000, Hau wrote:
> >>>>>>>>> In this application(rtl8168h + rtl8211fs) it also supports
> >>>>>>>>> 100Mbps fiber
> >>>>>>>> module.
> >>>>>>>>
> >>>>>>>> Does RTL8211FS advertise 100Mbps and 1Gbps on the UTP/MDI
> side
> >> in
> >>>>>>>> case of a 100Mbps fiber module?
> >>>>>>> Yes.
> >>>>>>>
> >>>>>> I think in this case internal PHY and RTL8211FS would negotiate
> >>>>>> 1Gbps, not matching the speed of the 100Mbps fiber module.
> >>>>>> How does this work?
> >>>>
> >>>> My mistake. With 100Mbps fiber module RTL8211FS will only advertise
> >>>> 100Mbps on the UTP/MDI side. With 1Gbps fiber module it will
> >>>> advertise both 100Mbps and 1Gbps. So issue will only happen with
> >>>> 1Gbps
> >> fiber module.
> >>>>
> >>>>> Fibre line side has no autoneg. Both ends need to be using the
> >>>>> same speed, or the SERDES does not synchronise and does not
> establish link.
> >>>>>
> >>>>> You can ask the SFP module what baud rate it supports, and then
> >>>>> use anything up to that baud rate. I've got systems where the SFP
> >>>>> is fast enough to support a 2.5Gbps link, so the MAC indicates
> >>>>> both 2.5G and 1G, defaults to 2.5G, and fails to connect to a 1G
> >>>>> link peer. You need to use ethtool to force it to the lower speed
> >>>>> before the
> >> link works.
> >>>>>
> >>>>> But from what i understand, you cannot use a 1000Base-X SFP, set
> >>>>> the MAC to 100Mbps, and expect it to connect to a 100Base-FX SFP.
> >>>>> So for me, the RTL8211FS should not be advertise 100Mbps and
> >>>>> 1Gbps, it needs to talk to the SFP figure out exactly what it is,
> >>>>> and only advertise the one mode which is supported.
> >>>>
> >>>> It is the RTL8211FS firmware bug. This patch is for workaround this issue.
> >>>
> >>> So if it is advertising both 100Mbps and 1Gbps, we know the SFP is
> >>> actually 1G, and we can remove the 100Mbps advertisement? That
> >>> should then solve all the problems?
> >>>
> >> Right, that's what I proposed too, removing 1Gbps advertisement of
> >> the RTL8168H-internal PHY via userspace tool, e.g. ethtool. For me
> >> this is the cleanest solution. Adding a workaround for a firmware bug
> >> of a specific external PHY to the r8169 MAC driver would be somewhat
> hacky.
> >>
> > Thanks for your suggestions. But because it needs user to execute
> userspace tool.
> > This workaround may not be accepted by our customer
> >
> 
> In this case you can provide your customer with a downstream kernel
> including your patch.
> 
Thanks. We will include it as one of the options.

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