Regarding Ethernet, we enabled link partner advertisement to include 1000Mbps, but still negotiated to 100Mbps.
The console log is below.
 
root@nxp-imx8:~# phytool write eth0/0/0x0000 0x1140
root@nxp-imx8:~# phytool read eth0/0/0x0000
0x1140
root@nxp-imx8:~# fec 5b040000.ethernet eth0: Link is Down
TI DP83867 5b040000.ethernet-1:00: Downshift occurred from negotiated speed 1Gbps to actual speed 100Mbps, check cabling!
fec 5b040000.ethernet eth0: Link is Up - 100Mbps/Full (downshifted) - flow control rx/tx
root@nxp-imx8:~#
root@nxp-imx8:~# 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: Symmetric Receive-only
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Auto-negotiation: on
        master-slave cfg: preferred slave
        master-slave status: slave
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: external
        MDI-X: Unknown
        Supports Wake-on: g
        Wake-on: d
        Link detected: yes
root@nxp-imx8:~#
root@nxp-imx8:~#

Best Regards,
Jason