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

[Conor Dooley]

On Wed, Jun 03, 2026 at 06:29:27PM +0200, Miquel Raynal wrote:
> 
> >> >> > 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?

I was talking about a scenario where you want to use the tuned mode to
achieve the maximum rate because of the device and/or board configuration,
but the rate is below the point where the controller would need tuning.
Say the controller needs tuning above 8 Hz but the conditions require
tuning to achieve more than 5 Hz. In this example, if the device can do
6 Hz, spi-max-frequency (in the current form) would be set to 6 Hz, and
the controller would not enable the tuned mode, leading to problems
because the inflection point determined from the controller compatible
of 8 Hz would not have been reached.

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