Richard Dawe [off-list ref] :
[...]

This particular code is to support the "media" option for the r8169 
module. The "media" option is marked as deprecated in favour of ethtool.

The current code is supposed to provide via ethtool the same function that
the media option did in Realtek's version of the driver (i.e. mostly a
current 'ethtool -s ethX autoneg off speed foo duplex bar').

Afaik, neither in Realtek's code nor in the current in-kernel driver does
the (obsolescent) "media" code do what one would expect from a "media"
option.

--
Ueimor