Re: [PATCH net v4 2/2] net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery

[Petr Wozniak]

Maxime Chevallier wrote:
> I finally got time to test this with a RollBall module, and I
> confirm what Aleksander says, the RollBall module's PHY doesn't
> get detected even with this patch. It does work on v7.0 though,
> so before the bridge probing was introduced.

Thanks a lot for taking the time to test, Maxime - and Aleksander
for the original report.

That settles it: the deferred-probe approach in patch 2/2 doesn't
actually restore genuine RollBall PHY detection, and as you both
confirm it worked before 8fe125892f40 introduced the bridge probing.
Sashiko's static review flagged the same thing (the probe bypasses the
PHY discovery retry loop for slow-initializing modules), so the static
analysis and the two hardware reports all point at the same flaw.

I only have RTL8261BE-based copper modules here, not a genuine RollBall
one, so I can't develop and verify a proper slow-init timing fix
(module_t_wait / a retry that waits for the bridge) without the
hardware to test against.

Given that, my suggestion:

- Please drop patch 2/2 from the series.

- Since 8fe125892f40 regressed genuine RollBall detection and the
  deferred probe doesn't restore it, I think the cleanest fix is to
  revert 8fe125892f40. I'm happy to send that revert if you'd prefer.
  The 5-minute RTL8261BE probe loop it was addressing is handled in our
  downstream tree, so reverting it upstream is fine on our side.

- Patch 1/2 (the mii_bus leak fix) is independent of all this and
  already has Reviewed-by from Maxime and Larysa - it would be good to
  take that one regardless. I can resend it standalone if that's easier.

A proper fix covering slow-firmware modules really needs a genuine
RollBall module to validate, so it's better owned by someone who has
that hardware - happy to help review.

Thanks again,
Petr