On 31/08/2022 20:36, Jakub Kicinski wrote:

On Wed, 31 Aug 2022 14:01:10 +0300 Gal Pressman wrote:

quoted

When autoneg is disabled (and auto fec enabled), the firmware chooses
one of the supported modes according to the spec. 

Would you be able to provide the pointer in the spec / section which
defines the behavior?  It may be helpful to add that to the kdoc for 
ETHTOOL_FEC_AUTO_BIT.

I have been directed to:
https://www.snia.org/technology-communities/sff/specifications?field_doc_status_value=All&combine=8024&field_release_date_value_2%5Bvalue%5D%5Bdate%5D=&field_release_date_value%5Bvalue%5D%5Bdate%5D=&items_per_page=20

SFF-8024 SFF Module Management Reference Code Tables -> Table 4-4
Extended Specification Compliance Codes.