Re: [PATCH net-next v2 3/3] net: mdio: treat PSE EPROBE_DEFER as non-fatal during PHY registration

Andrew Lunn
2026-04-03T15:16:20Z

On Fri, Apr 03, 2026 at 03:31:11PM +0200, Carlo Szelinsky wrote:
> Hi Andrew,
>
> Thx for helping me!
> I thought of keeping the eager path so we still catch broken DT bindings
> early at boot instead of silently failing later on first ethtool access.
> But you're right, dropping it would simplify things quite a bit. Do you
> think that trade-off is worth it? I will follow your lead.

I suppose, the real question is, are we fixing the correct thing?

As a general principal in Linux, you don't register a device with the
core until it has all the resources it needs. This is what
EPROBE_DEFFER is about. If it is not registered with the core, the
uAPI is not available, making user space simpler.

As i understand the problem, by deferring the probe, the regulator
gets turned off, cutting the power?

So is the real problem with the regulator code? Do we need a way to
indicate a regulator should not be turned off if it is unused?

Or can we change when the regulator code turns off unused regulators?
I don't remember all the details for deferred probing, but i thought
the driver core had a timer and would keep running the deferred probes
until that timer expires. When does the regulator code turn off unused
regulators relative to this timer?

Andrew