Hi,

If the lan78xx driver is compiled into the kernel and the network cable is
plugged in at boot, /sys/class/net/eth0/carrier is stuck at 1 and doesn't
toggle if the cable is unplugged and replugged.

If the network cable is *not* plugged in at boot, all seems to work fine.
I.e., post-boot cable plugs and unplugs toggle the carrier flag.

Also, everything seems to work fine if the driver is compiled as a module.

There's an older ticket for the raspi kernel [1] but I've just tested this
with a 5.8 kernel on a Pi 3B+ and still see that behavior.

...Juerg

[1] https://github.com/raspberrypi/firmware/issues/1100