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

[Sean Anderson]

On 6/23/25 14:27, Andrew Lunn wrote:
> On Mon, Jun 23, 2025 at 11:16:08AM -0400, Sean Anderson wrote:
>> 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.
> 
> O.K. So why not change the order so that you know you have all the
> needed dependencies before registering the MDIO bus?
> 
> Quoting your previous email:
> 
>> Returning EPROBE_DEFER after probing a bus may result in an infinite
>> probe loop if the EPROBE_DEFER error is never resolved. For example,
>> if the PCS is located on another MDIO bus and that MDIO bus is
>> missing its driver then we will always return EPROBE_DEFER.
> 
> Why not get a reference on the PCS device before registering the MDIO
> bus?

Because the PCS may be on the MDIO bus. This is probably the most-common
case.

--Sean