MDIO on GPIOs

Yes

In some cases, due to the limited resources allocated by imx pins, gpio has to be used as mdio/mdc.

This article is a simple guide on how to use MDIO on GPIOs.

The demo code is for network fec interface.

1. Add CONFIG_MDIO_GPIO=y and rebuild kernel

2. Modify fec device tree to use MDIO ON GPIO

FEC test result:

root@imx93evk:~# ethtool eth0

Settings for eth0:

Supported ports: [ TP MII ]

Supported link modes: 10baseT/Half 10baseT/Full

100baseT/Half 100baseT/Full

1000baseT/Full

Supported pause frame use: Symmetric

Supports auto-negotiation: Yes

Supported FEC modes: Not reported

Advertised link modes: 10baseT/Half 10baseT/Full

100baseT/Half 100baseT/Full

1000baseT/Full

Advertised pause frame use: Symmetric

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: No

Link partner advertised auto-negotiation: Yes

Link partner advertised FEC modes: Not reported

Speed: 1000Mb/s

Duplex: Full

Auto-negotiation: on

master-slave cfg: preferred slave

master-slave status: slave

Port: Twisted Pair

PHYAD: 2

Transceiver: external

MDI-X: Unknown

Supports Wake-on: g

Wake-on: d

Link detected: yes

root@imx93evk:~# ifconfig

eth0: flags=-28605<UP,BROADCAST,RUNNING,MULTICAST,DYNAMIC> mtu 1500

inet 10.192.246.129 netmask 255.255.255.0 broadcast 10.192.246.255

inet6 fe80::885a:aeff:fea3:7dcf prefixlen 64 scopeid 0x20<link>

ether 8a:5a:ae:a3:7d:cf txqueuelen 1000 (Ethernet)

RX packets 13 bytes 2294 (2.2 KiB)

RX errors 0 dropped 3 overruns 0 frame 0

TX packets 25 bytes 4691 (4.5 KiB)

TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eth1: flags=-28669<UP,BROADCAST,MULTICAST,DYNAMIC> mtu 1500

ether a2:5e:45:17:72:79 txqueuelen 1000

eQOS test result

imx93evk login: root
root@imx93evk:~# ifconfig
eth0: flags=-28669<UP,BROADCAST,MULTICAST,DYNAMIC> mtu 1500
ether 00:04:9f:08:7f:d0 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eth1: flags=-28605<UP,BROADCAST,RUNNING,MULTICAST,DYNAMIC> mtu 1500
inet 10.192.246.112 netmask 255.255.255.0 broadcast 10.192.246.255
inet6 fe80::204:9fff:fe08:7fcf prefixlen 64 scopeid 0x20<link>
ether 00:04:9f:08:7f:cf txqueuelen 1000 (Ethernet)
RX packets 12 bytes 3020 (2.9 KiB)
RX errors 0 dropped 3 overruns 0 frame 0
TX packets 31 bytes 5355 (5.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 104

root@imx93evk:~# ethtool eth1
Settings for eth1:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
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/Full
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: No
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Auto-negotiation: on
master-slave cfg: preferred slave
master-slave status: slave
Port: Twisted Pair
PHYAD: 1
Transceiver: external
MDI-X: Unknown
Supports Wake-on: ug
Wake-on: d
Current message level: 0x0000003f (63)
drv probe l