Date:   Mon, 06 Dec 2021 18:26:25 +0000
From:   Martyn Welch <martyn.welch@...labora.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>, netdev@...r.kernel.org,
        kernel@...labora.com, Russell King <rmk+kernel@...linux.org.uk>
Subject: Re: mv88e6240 configuration broken for B850v3

On Mon, 2021-12-06 at 17:44 +0000, Martyn Welch wrote:
> On Fri, 2021-12-03 at 17:25 +0100, Andrew Lunn wrote:
> > > Hi Andrew,
> > 
> > Adding Russell to Cc:
> > 
> > > I'm currently in the process of updating the GE B850v3 [1] to run
> > > a
> > > newer kernel than the one it's currently running. 
> > 
> > Which kernel exactly. We like bug reports against net-next, or at
> > least the last -rc.
> > 
> 
> I tested using v5.15-rc3 and that was also affected.
> 

I've just tested v5.16-rc4 (sorry - just realised I previously wrote
v5.15-rc3, it was v5.16-rc3...) and that was exactly the same.

> > > 
> > > This device (and others in the same family) use a mv88e6240
> > > switch to
> > > provide a number of their ethernet ports. The CPU link on the
> > > switch
> > > is
> > > connected via a PHY, as the network port on the SoM used is
> > > exposed
> > > via
> > > a PHY.
> > > 
> > > The ports of the B850v3 stopped working when I upgraded,
> > > bisecting
> > > resulted in me finding that this commit was the root cause:
> > > 
> > > 3be98b2d5fbc (refs/bisect/bad) net: dsa: Down cpu/dsa ports
> > > phylink
> > > will control
> > > 
> > > I think this is causing the PHY on the mv88e6240 side of the CPU
> > > link
> > > to be forced down in our use case.
> > > 
> > > I assume an extra check is needed here to stop that in cases like
> > > ours,
> > > though I'm not sure what at this point. Any ideas?
> > 
> > From the commit message.
> > 
> >     DSA and CPU ports can be configured in two ways. By default,
> > the
> >     driver should configure such ports to there maximum bandwidth.
> > For
> >     most use cases, this is sufficient. When this default is
> > insufficient,
> >     a phylink instance can be bound to such ports, and phylink will
> >     configure the port,
> > 
> > You have a phy-handle in your node:
> > 
> >         port@4 {
> >                 reg = <4>;
> >                 label = "cpu";
> >                 ethernet = <&switch_nic>;
> >                 phy-handle = <&switchphy4>;
> >         };
> > 
> > so i would expect there to be a phylink instance. The commit
> > message
> > continues to say:
> > 
> >                                           and phylink will
> >     configure the port, e.g. based on fixed-link properties.
> > 
> > So i think you are asking the wrong question. It is not an extra
> > check
> > is needed here, we need to understand why phylink is not
> > configuring
> > the MAC. Or is that configuration wrong.
> > 
> > I suggest you add #define DEBUG 1 to the very top of
> > drivers/net/phy/phylink.c so we can see what phylink is doing.
> > 
> 
> The pertinent parts of the logs (from v5.16-rc3, with the above debug
> added) appear to be:
> 
> # dmesg | grep -e mv88e6085 -e DSA -e libphy
> [    2.119282] libphy: Fixed MDIO Bus: probed
> [    2.124547] libphy: GPIO Bitbanged MDIO: probed
> [    2.129795] mv88e6085 gpio-0:00: switch 0x2400 detected: Marvell
> 88E6240, revision 1
> [    2.150568] libphy: mdio: probed
> [    2.224233] libphy: fec_enet_mii_bus: probed
> [    3.064455] mv88e6085 gpio-0:00: switch 0x2400 detected: Marvell
> 88E6240, revision 1
> [    3.083930] libphy: mdio: probed
> [    3.844882] mv88e6085 gpio-0:00 eneport1 (uninitialized): PHY
> [!mdio-gpio!switch@...dio:00] driver [Marvell 88E1540] (irq=362)
> [    3.856335] mv88e6085 gpio-0:00 eneport1 (uninitialized): phy:
> setting supported 0000000,00000000,000022ef advertising
> 0000000,00000000,000022ef
> [    3.962649] mv88e6085 gpio-0:00 eneport2 (uninitialized): PHY
> [!mdio-gpio!switch@...dio:01] driver [Marvell 88E1540] (irq=363)
> [    3.974091] mv88e6085 gpio-0:00 eneport2 (uninitialized): phy:
> setting supported 0000000,00000000,000022ef advertising
> 0000000,00000000,000022ef
> [    4.080405] mv88e6085 gpio-0:00 enix (uninitialized): PHY
> [!mdio-gpio!switch@...dio:02] driver [Marvell 88E1540] (irq=364)
> [    4.091510] mv88e6085 gpio-0:00 enix (uninitialized): phy: setting
> supported 0000000,00000000,000022ef advertising
> 0000000,00000000,000022ef
> [    4.202683] mv88e6085 gpio-0:00 enid (uninitialized): PHY
> [!mdio-gpio!switch@...dio:03] driver [Marvell 88E1540] (irq=365)
> [    4.213774] mv88e6085 gpio-0:00 enid (uninitialized): phy: setting
> supported 0000000,00000000,000022ef advertising
> 0000000,00000000,000022ef
> [    4.298209] mv88e6085 gpio-0:00: PHY [!mdio-gpio!switch@...dio:04]
> driver [Marvell 88E1540] (irq=366)
> [    4.307475] mv88e6085 gpio-0:00: phy: setting supported
> 0000000,00000000,000022ef advertising 0000000,00000000,000022ef
> [    4.314285] mv88e6085 gpio-0:00: configuring for phy/ link mode
> [    4.320251] mv88e6085 gpio-0:00: major config 
> [    4.320262] mv88e6085 gpio-0:00: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [    4.324265] DSA: tree 0 setup
> [    4.399423] mv88e6085 gpio-0:00: phy link down
> /Unknown/Unknown/off
> [   15.600977] mv88e6085 gpio-0:00 enix: configuring for phy/ link
> mode
> [   15.607417] mv88e6085 gpio-0:00 enix: major config 
> [   15.607443] mv88e6085 gpio-0:00 enix: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [   15.678811] mv88e6085 gpio-0:00 enix: phy link down
> /Unknown/Unknown/off
> [   15.961559] mv88e6085 gpio-0:00 enid: configuring for phy/ link
> mode
> [   15.967945] mv88e6085 gpio-0:00 enid: major config 
> [   15.967958] mv88e6085 gpio-0:00 enid: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [   15.986370] mv88e6085 gpio-0:00 enix: configuring for phy/ link
> mode
> [   15.992829] mv88e6085 gpio-0:00 enix: major config 
> [   15.992843] mv88e6085 gpio-0:00 enix: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [   16.019628] mv88e6085 gpio-0:00 eneport2: configuring for phy/
> link
> mode
> [   16.026370] mv88e6085 gpio-0:00 eneport2: major config 
> [   16.026382] mv88e6085 gpio-0:00 eneport2: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [   16.057585] mv88e6085 gpio-0:00 eneport1: configuring for phy/
> link
> mode
> [   16.064367] mv88e6085 gpio-0:00 eneport1: major config 
> [   16.064381] mv88e6085 gpio-0:00 eneport1: phylink_mac_config:
> mode=phy//Unknown/Unknown adv=0000000,00000000,00000000 pause=00
> link=0
> an=0
> [   16.132700] mv88e6085 gpio-0:00 enid: phy link up /10Mbps/Full/off
> [   16.134210] mv88e6085 gpio-0:00 enid: phylink_mac_config:
> mode=phy//10Mbps/Full adv=0000000,00000000,00000000 pause=00 link=1
> an=0
> [   16.141177] mv88e6085 gpio-0:00 enid: Link is Up - 10Mbps/Full -
> flow control off
> [   16.195201] mv88e6085 gpio-0:00 enix: phy link down
> /Unknown/Unknown/off
> [   16.215131] mv88e6085 gpio-0:00 eneport2: phy link down
> /Unknown/Unknown/off
> [   16.254004] mv88e6085 gpio-0:00 eneport1: phy link up
> /10Mbps/Full/off
> [   16.254027] mv88e6085 gpio-0:00 eneport1: phylink_mac_config:
> mode=phy//10Mbps/Full adv=0000000,00000000,00000000 pause=00 link=1
> an=0
> [   16.254056] mv88e6085 gpio-0:00 eneport1: Link is Up - 10Mbps/Full
> -
> flow control off
> [   18.706700] mv88e6085 gpio-0:00: phy link up /1Gbps/Full/rx/tx
> [   18.708976] mv88e6085 gpio-0:00: phylink_mac_config:
> mode=phy//1Gbps/Full adv=0000000,00000000,00000000 pause=03 link=1
> an=0
> [   18.709002] mv88e6085 gpio-0:00: Link is Up - 1Gbps/Full - flow
> control rx/tx
> 
> Despite the last few lines suggesting to me the phy link is up, I'm
> unable to access the network I'd expect to be able to access.
> 
> >         Andrew
> > 
> 

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