[PATCH v3 02/13] spi: dt-bindings: cdns,qspi-nor: add PHY tuning pattern partition property

[Rob Herring]

On Wed, Jun 3, 2026 at 11:01 AM Miquel Raynal <miquel.raynal at bootlin.com> wrote:
>
> Hello,
>
> On 02/06/2026 at 11:49:45 -05, Rob Herring <robh at kernel.org> wrote:
>
> > On Wed, May 27, 2026 at 11:25:16PM +0530, Santhosh Kumar K wrote:
> >> PHY tuning requires a known data pattern to be readable from flash.
> >> When no partition is explicitly identified, the controller must search
> >> all available partitions to locate the pattern by label, which adds
> >> overhead and relies on label naming conventions outside the
> >> controller's control.
> >
> > I agree 'label' is not the best choice. Software should not care what
> > 'label' contains. It should really be 'compatible' instead.
>
> But compatible does not seem relevant in this case, right? We are just
> flagging the location of "some useful data for the controller".

compatible is what tells us what a region contains and how to use it.
That seems exactly what we need to define here.

> >> Add cdns,phy-pattern-partition, a phandle property that allows the DT
> >> author to directly reference the flash partition holding the PHY tuning
> >> pattern. The controller uses this partition during calibration, avoiding
> >> the partition search entirely.
> >
> > Do you have any data that this approach being "direct" is faster? In
> > fact, it might be worse. Instead of searching just the limited number of
> > partition subnodes, you now search the entire tree for a matching
> > phandle value. We do have phandle caching, so that might save you
> > here.
>
> True, but besides performance considerations, I personally do not find
> elegant using a partition name/label, but maybe that's just personal
> taste :-)

I agree. That's true for all the partition nodes with only node name
or label to go on. We should fix that at the source. However, you
already have to support using label, so anything else is supporting a
2nd way whether it is compatible or a phandle property. Is it really
worth it here?

Rob