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

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello,

On 02/06/2026 at 11:49:45 -05, Rob Herring <robh@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".

>> 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 :-)

Thanks,
Miquèl

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