sun7i-dwmac: link detection failure with 1000Mbit parters

[Priit Laes]

Heya!

I have noticed that with sun7i-dwmac driver (OLinuxino Lime2 eMMC), link
detection fails consistently with certain 1000Mbit partners (for example Huawei
B525s-23a 4g modem ethernet outputs and RTL8153-based USB3.0 ethernet dongle),
but the same hardware works properly with certain other link partners (100Mbit GL AR150
for example).

(Just need to test with another 1000Mbit switch at the office).

I first thought it could be a regression, but I went from current master to as far back
as 5.2.0-rc6 where it was still broken.

Failure is basically following:

[ 10.971485] sun7i-dwmac 1c50000.ethernet eth0: PHY [stmmac-0:01] driver [Generic PHY]
[ 10.980841] sun7i-dwmac 1c50000.ethernet eth0: No Safety Features support found
[ 10.988291] sun7i-dwmac 1c50000.ethernet eth0: RX IPC Checksum Offload disabled
[ 10.995694] sun7i-dwmac 1c50000.ethernet eth0: No MAC Management Counters available
[ 11.003381] sun7i-dwmac 1c50000.ethernet eth0: PTP not supported by HW
[ 11.009927] sun7i-dwmac 1c50000.ethernet eth0: configuring for phy/rgmii link mode
... link and activity leds go blank ...
... remove and replug and link is detected again ...
[ 19.371894] sun7i-dwmac 1c50000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx

Ethtool output in case link is down:
[snip]
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: Unknown!
Duplex: Unknown! (255)
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: d
Wake-on: d
Current message level: 0x0000003f (63)
drv probe link timer ifdown ifup
Link detected: no
[/snip]

And ethtool output in case cable is removed and replugged:
[snip]
ethtool eth0
Settings for eth0:
...cut...
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Link partner advertised pause frame use: Symmetric
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: d
Wake-on: d
Current message level: 0x0000003f (63)
drv probe link timer ifdown ifup
Link detected: yes
[/snip]


With 100Mbit link partner (GL Inet AR150), the link is pulled up almost
immediately:
[ 15.531754] sun7i-dwmac 1c50000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx

[snip]
Settings for eth0:
... cut ...
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 100Mb/s
Duplex: Full
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: d
Wake-on: d
Current message level: 0x0000003f (63)
drv probe link timer ifdown ifup
Link detected: yes
[/snip]

[Andrew Lunn]

On Wed, Oct 30, 2019 at 08:21:17PM +0000, Priit Laes wrote:
> Heya!
>
> I have noticed that with sun7i-dwmac driver (OLinuxino Lime2 eMMC), link
> detection fails consistently with certain 1000Mbit partners (for example Huawei
> B525s-23a 4g modem ethernet outputs and RTL8153-based USB3.0 ethernet dongle),
> but the same hardware works properly with certain other link partners (100Mbit GL AR150
> for example).

Hi Pritt

What PHY is used? And what happens if you use the specific PHY driver,
not the generic PHY driver?

Andrew

[Andrew Lunn]

Schematics of the board are here:

https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A20-OLinuXino-LIME2/1.%20Latest%20hardware%20revision/A20-OLinuXino-Lime2_Rev_K2_COLOR.pdf

So it has a KSZ9031. The micrel driver supports that device. And there
is a patch which might be relevant:

ommit 3aed3e2a143c9619f4c8d0a3b8fe74d7d3d79c93
Author: Antoine Tenart <antoine...@bootlin.com>
Date: Tue Apr 16 12:10:20 2019 +0200

net: phy: micrel: add Asym Pause workaround

The Micrel KSZ9031 PHY may fail to establish a link when the Asymmetric
Pause capability is set. This issue is described in a Silicon Errata
(DS80000691D or DS80000692D), which advises to always disable the
capability. This patch implements the workaround by defining a KSZ9031
specific get_feature callback to force the Asymmetric Pause capability
bit to be cleared.

This fixes issues where the link would not come up at boot time, or when
the Asym Pause bit was set later on.

Signed-off-by: Antoine Tenart <antoine...@bootlin.com>
Reviewed-by: Andrew Lunn <and...@lunn.ch>
Reviewed-by: Florian Fainelli <f.fai...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>


Please test using the Micrel PHY driver and see if that solves your
problem.

Andrew

[Priit Laes]

On Thu, Oct 31, 2019 at 02:14:04PM +0100, Andrew Lunn wrote:
> On Thu, Oct 31, 2019 at 02:04:22PM +0100, Andrew Lunn wrote:
> > On Wed, Oct 30, 2019 at 08:21:17PM +0000, Priit Laes wrote:
> > > Heya!
> > >
> > > I have noticed that with sun7i-dwmac driver (OLinuxino Lime2 eMMC), link
> > > detection fails consistently with certain 1000Mbit partners (for example Huawei
> > > B525s-23a 4g modem ethernet outputs and RTL8153-based USB3.0 ethernet dongle),
> > > but the same hardware works properly with certain other link partners (100Mbit GL AR150
> > > for example).
> >
> > Hi Pritt
> >
> > What PHY is used? And what happens if you use the specific PHY driver,
> > not the generic PHY driver?
>
> Schematics of the board are here:
>
> https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A20-OLinuXino-LIME2/1.%20Latest%20hardware%20revision/A20-OLinuXino-Lime2_Rev_K2_COLOR.pdf
>
> So it has a KSZ9031. The micrel driver supports that device. And there
> is a patch which might be relevant:
>

> commit 3aed3e2a143c9619f4c8d0a3b8fe74d7d3d79c93
> Author: Antoine Tenart <antoine...@bootlin.com>
...

> Please test using the Micrel PHY driver and see if that solves your
> problem.

Thanks, CONFIG_MICREL_PHY=y helped!

>
> Andrew

[Priit Laes]

On Thu, Oct 31, 2019 at 10:38:41AM +0000, Russell King - ARM Linux admin wrote:
> On Thu, Oct 31, 2019 at 08:39:06AM +0000, Jose Abreu wrote:
> > ++ Florian, Andrew, Heiner, Russell
> >
> > Can you please attach your dmesg log ? PHYLINK provides some useful
> > debug logs.

> >
> > From: Priit Laes <pl...@plaes.org>
> > Date: Oct/30/2019, 20:21:17 (UTC+00:00)
> >
> > > Heya!
> > >
> > > I have noticed that with sun7i-dwmac driver (OLinuxino Lime2 eMMC), link
> > > detection fails consistently with certain 1000Mbit partners (for example Huawei
> > > B525s-23a 4g modem ethernet outputs and RTL8153-based USB3.0 ethernet dongle),
> > > but the same hardware works properly with certain other link partners (100Mbit GL AR150
> > > for example).
> > >
> > > (Just need to test with another 1000Mbit switch at the office).
> > >
> > > I first thought it could be a regression, but I went from current master to as far back
> > > as 5.2.0-rc6 where it was still broken.
>

> The stmmac conversion to phylink was v5.3-rc1, so that's likely not the
> issue if v5.2-rc6 also exhibits this behaviour.
>
> My guess is that the problem lies in phylib, especially as the link LEDs
> go off when the link is configured. I notice that it's using the
> generic PHY driver rather than a specific driver.

Yup, it turned out to be a phy-related issue - I was using generic PHY
driver, but the board is using Micrel KSZ9031 which has some quirks that
MICREL_PHY=y managed to work around.

>
> mii-diag -v eth0
>
> would be useful to see for the case where the link has failed, without
> replugging the ethernet cable.

mii-diag seems to be quite an useful tool, but unfortunately has not been
packaged anymore on newer distro releases like Debian stable and latest
Ubuntu LTS.

>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up