Re: [PATCH net-next v8 1/1] Documentation: net: add flow control guide and document ethtool API

From: Jakub Kicinski

Date: Thu Nov 27 2025 - 20:21:41 EST


On Thu, 27 Nov 2025 16:14:15 +0000 Russell King (Oracle) wrote:
> > > * **Constraint Checking:**
> > > * Drivers should reject a non-zero setting of @autoneg when
> > > * autonegotiation is disabled (or not supported) for the link.
> > > * Drivers should reject unsupported rx/tx combinations with -EINVAL.
>
> Definitely not. Drivers should accept autoneg=1 because that is the
> user stating "my desire is to use the result of autonegotiation when
> it becomes available". Just because autoneg may be disabled doesn't
> mean it will remain disabled, and having to issue ethtool commands
> in the right sequence leads to poor user experiences.

It's an existing recommendation, coming from 6a7a1081cebacc4.
I thought it's just because of the ambiguity what the settings mean
with autoneg on or off. But looks like Ben has been trying to push
people towards link mode bits 11 years ago already :(