[dpdk-dev] Questions about reporting auto-negotiation capability

[Thomas Monjalon]

29/03/2021 09:03, Thomas Monjalon:
> 29/03/2021 06:02, Huisong Li:
> >          'speed_capa' in struct rte_eth_dev_info is defined as follows:
> > 
> > uint32_t speed_capa;  /**< Supported speeds bitmap (ETH_LINK_SPEED_). */
> > 
> > 
> >        Most PMD drivers use this field to report the speeds capability 
> > supported by the device to the upper-layer app.
> > 
> > But it seems that few NICs report their auto-negotiation capability 
> > through this field. If NIC also uses it to report
> > their auto-negotiation capability through this field, and should set it 
> > to ETH_LINK_SPEED_AUTONEG(0) based on
> > the definition of ETH_LINK_SPEED_xxx. In this case, it conflicts the 
> > report of the speeds capability .
> > 
> > I don't know how to correctly report the auto-negotiation capability of 
> > the device. Thanks for your reply.
> 
> ETH_LINK_SPEED_AUTONEG is not for capabilities.
> Anyway, if it is set, it changes nothing (0) in the bitmap.
> I see mlx5 is wrongly using it.
> 
> speed_capa is only for enumerating speeds.

I see some drivers are advertising ETH_LINK_SPEED_FIXED in speed_capa
if the device cannot support autonegotiation.
Should we add a note in doxygen?