Re: [PATCH] of_mdio: Fix broken PHY IRQ in case of probe deferral

Geert Uytterhoeven
2017-05-18T20:36:19Z

Hi Andrew,

On Thu, May 18, 2017 at 9:34 PM, Andrew Lunn <andrew@lunn.ch> wrote:
>> > This most certainly works fine in the simple case where you have one PHY
>> > hanging off the MDIO bus, now what happens if you have several?
>> >
>> > Presumably, the first PHY that returns EPROBE_DEFER will make the entire
>> > bus registration return EPROB_DEFER as well, and so on, and so forth,
>> > but I am not sure if we will be properly unwinding the successful
>> > registration of PHYs that either don't have an interrupt, or did not
>> > return EPROBE_DEFER.
>> >
>> > It should be possible to mimic this behavior by using the fixed PHY, and
>> > possibly the dsa_loop.c driver which would create 4 ports, expecting 4
>> > fixed PHYs to be present.
>>
>> mdiobus_unregister(), called from of_mdiobus_register() on failure,
>> should do the unwinding, right?
>>
>> And when the driver is reprobed, all PHYs are reprobed, until they all
>> succeed.
>
> That is the theory. I looked at that while reviewing the patch. But
> this has probably not been tested in anger. It would be good to test
> this properly, with not just the first PHY returning -EPROBE_DEFER, to
> really test the unwind.

Unfortunately I don't have a board with multiple PHYs, so I cannot test
that case.

Does unbinding/rebinding a network driver with multiple PHYs currently
work? Or module unload/reload?

That should exercise a similar code path.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds