RE: [PATCH net-next] net: ethtool: add support for forward error correction modes

+/**
+ * struct ethtool_fecparam - Ethernet forward error correction(fec)
+parameters
+ * @cmd: Command number = %ETHTOOL_GFECPARAM or
%ETHTOOL_SFECPARAM
+ * @active_fec: FEC mode which is active on porte
+ * @fec: Bitmask of supported/configured FEC modes
+ * @rsvd: Reserved for future extensions. i.e FEC bypass feature.
+ *
+ * Drivers should reject a non-zero setting of @autoneg when
+ * autoneogotiation is disabled (or not supported) for the link.
+ *
+ */

Why request this from drivers?
Can't you reject such configuration requests in the ethtool-core?