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:

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Hi Andrew,

Adding Russell to Cc:

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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.

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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@0!mdio: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@0!mdio: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@0!mdio: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@0!mdio: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@0!mdio: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.

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        Andrew