Hello,
I try to force the configuration of the Ethernet PHY to 100Mbs full duplex and deactivated the auto-negotiation. When I do that the link status of the PHY pass at down and I don't arrive to switch it back to up again except if I reset the PHY (the reset clear my modification of register).
I work on the TQMa8Xx (Imx8x), the PHY is a dp83867is. To force the config to what I needed I modified the Basic Mode Control Register (address 0).
Regards
Alexandre