[PATCH v2] net: mtk_sgmii: implement mtk_pcs_ops

[Russell King (Oracle)]

On Sat, Oct 22, 2022 at 12:52:00PM +0200, Frank Wunderlich wrote:
> > Gesendet: Samstag, 22. Oktober 2022 um 11:11 Uhr
> > Von: "Russell King (Oracle)" <linux at armlinux.org.uk>
> 
> > Please try this untested patch, which should setup the PCS to perform
> > autonegotiation when using in-band mode for 1000base-X, write the
> > correct to offset 8, and set the link timer correctly.
> 
> hi,
> 
> this patch breaks connectivity at least on the sfp-port (eth1).
> 
> root at bpi-r3:~# ip link set eth1 up
> [   65.457521] mtk_soc_eth 15100000.ethernet eth1: configuring for inband/1000base-x link mode
> root at bpi-r3:~# [   65.522936] offset:0 0x2c1140
> [   65.522950] offset:4 0x4d544950
> [   65.525914] offset:8 0x40e041a0
> [   65.529064] mtk_soc_eth 15100000.ethernet eth1: Link is Up - 1Gbps/Unknown - flow control off
> [   65.540733] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
> 
> root at bpi-r3:~# ip a a 192.168.0.19/24 dev eth1
> root at bpi-r3:~# ip r a default via 192.168.0.10
> root at bpi-r3:~# iperf3 -c 192.168.0.21 #ping does not work too
> iperf3: error - unable to send control message: Bad file descriptor
> root at bpi-r3:~# ethtool eth1
> [  177.346183] offset:0 0x2c1140
> [  177.346202] offset:4 0x4d544950
> Settings for eth[  177.349168] offset:8 0x40e041a0
> 1:
>         Supported p[  177.352477] offset:0 0x2c1140
> [  177.356952] offset:4 0x4d544950
> 
>         Supported link modes:   1000baseX/Full
>         Supported pause frame use: Symmetric Receive-only
>         Supports auto-negotiation: Yes
>         Supported FEC modes: Not reported
>         Advertised link modes:  1000baseX/Full
>         Advertised pause frame use: Symmetric Receive-only
>         Advertised auto-negotiation: Yes
>         Advertised FEC modes: Not reported
>         Speed: 1000Mb/s
>         Duplex: Unknown! (255)
>         Auto-negotiation: on
>         Port: FIBRE
>         PHYAD: 0
>         Transceiver: internal
>         Current message level: 0x000000ff (255)
>                                drv probe link timer ifdown ifup rx_err tx_err
>         Link detected: yes
> root at bpi-r3:~#
> 
> from sgmii_init
> [    1.091796] dev: 1 offset:0 0x81140
> [    1.094977] dev: 1 offset:4 0x4d544950
> [    1.098456] dev: 1 offset:8 0x1
> ...
> pcs_get_state
> [   65.522936] offset:0 0x2c1140
> [   65.522950] offset:4 0x4d544950
> [   65.525914] offset:8 0x40e041a0
> [  177.346183] offset:0 0x2c1140
> [  177.346202] offset:4 0x4d544950
> [  177.349168] offset:8 0x40e041a0
> [  177.352477] offset:0 0x2c1140
> [  177.356952] offset:4 0x4d544950

Hi,

Thanks. Well, the results suggest that the register at offset 8 is
indeed the advertisement and link-partner advertisement register. So
we have a bit of progress and a little more understanding of this
hardware.

Do you know if your link partner also thinks the link is up?

What I notice is:

mtk_soc_eth 15100000.ethernet eth1: Link is Up - 1Gbps/Unknown - flow control off

The duplex is "unknown" which means you're not filling in the
state->duplex field in your pcs_get_state() function. Given the
link parter adverisement is 0x00e0, this means the link partner
supports PAUSE, 1000base-X/Half and 1000base-X/Full. The resolution
is therefore full duplex, so can we hack that in to your
pcs_get_state() so we're getting that right for this testing please?

Now, I'm wondering what SGMII_IF_MODE_BIT0 and SGMII_IF_MODE_BIT5 do
in the SGMSYS_SGMII_MODE register. Does one of these bits set the
format for the 16-bit control word that's used to convey the
advertisements. I think the next step would be to play around with
these and see what effect setting or clearing these bits has -
please can you give that a go?

Thanks.

-- 
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