Re: [PATCH net 4/4] net: axienet: Split into MAC and MDIO drivers

[Sean Anderson <sean.anderson@linux.dev>]

On 6/21/25 03:33, Andrew Lunn wrote:
> On Thu, Jun 19, 2025 at 04:05:37PM -0400, Sean Anderson wrote:
>> Returning EPROBE_DEFER after probing a bus may result in an infinite
>> probe loop if the EPROBE_DEFER error is never resolved.
> 
> That sounds like a core problem. I also thought there was a time
> limit, how long the system will repeat probes for drivers which defer.
> 
> This seems like the wrong fix to me.

I agree. My first attempt to fix this did so by ignoring deferred probes
from child devices, which would prevent "recursive" loops like this one
[1]. But I was informed that failing with EPROBE_DEFER after creating a
bus was not allowed at all, hence this patch.

Limiting the number of deferred probe attempts (at least before
continuing to boot) is a good idea in theory, but would not address the
root of the issue. Setting a good threshold is not obvious, since there
are almost certainly systems out there that are missing some device
links and have a lot of deferred probes. 

--Sean

[1] https://lore.kernel.org/all/CAGETcx-koKBvSXTHChYYF-qSU-r1cBUbLghJZcqtJOGQZjn3BA@mail.gmail.com/