Due to some quirks with how I2C devices are probed, some devices like the RTC don’t always get loaded automatically.
These ones are often affected:
rtc_rx8025 # RTC
gpio_pca953x # GPIO expander for SFP, some lights and buttons (e.g ADMIN light/button)
i2c_mux_pca954x # I2C mux for SFP slots
There is also our out of tree sensor package, of which emc2301 is the most useful (for the fan speed controller).
(There is now a different emc2301 in the Linux kernel which has some issues. Beware!)
That one provides:
emc2301
emc181x
pac1934
emc17xx