[PATCH v3 01/13] spi: dt-bindings: allow spi-max-frequency to specify a frequency pair

[Miquel Raynal]

>> >> > The non-PHY frequency is a controller limitation/capability rather than
>> >> > a flash characteristic, so it seems more appropriate to keep it in the
>> >> > controller driver as Conor suggested.
>> >> 
>> >> The non tuned frequency is the maximum frequency one could use
>> >> reliably. It is not controller specific. It is mostly board specific,
>> >> and to some extend may also be chip specific.
>> >> 
>> >> The tuned frequency is the maximum frequency one could use reliably
>> >> after line a controller or chip specific training procedure. It is
>> >> also the result of an aggregated set of non discoverable hardware
>> >> limitations:
>> >> - board routing
>> >> - chip capability
>> >> - controller capability
>> >
>> > Right, and this I guess is what scuppers letting the controller driver
>> > sort the configuration out itself and leaving the property as-is.
>> > It could be that the speed in spi-max-frequency is lower than the "base
>> > speed" of the controller but because of board routing or device
>> > capability that the tuned mode is still required, right?
>> 
>> I do not actually expect any tuned mode/frequency to be mandatory.
>
> I think you misunderstood my use of "required", I meant that the new
> property/information was needed in the scenario I described, not that it
> should be a required property in a binding.

Yes I misunderstood the term indeed. However I still fail to catch what
you meant here, I'm sorry. Would you mind rephrasing?

Just to clarify, tuned modes are only bonuses.

Miquèl