Re: [PATCH 11/13] dt-bindings: lpspi: Update maximum num-cs value

[James Clark]

On 14/08/2025 9:59 pm, Rob Herring wrote:
> On Thu, Aug 14, 2025 at 05:06:51PM +0100, James Clark wrote:
> > As mentioned in commit f46b06e62c86 ("spi: spi-fsl-lpspi: Read
> > chip-select amount from hardware for i.MX93"), some devices support up
> > to 3 chip selects so update the max value.
> >
> > This isn't a fix or functional change because the devices with 3 chip
> > selects support reading the number of chip selects from hardware, so the
> > value wouldn't have needed to be set here. However the commit states
> > that the DT could be used to overwrite any HW value, so the full range
> > should be supported. This also avoids confusion for any readers about
> > how many chip selects there are.
>
> If reading the h/w gives you 3, when would the DT need to override that
> with 3? You only need an override for 2 or less.

Maybe it should say "currently the devices with 3 chip selects". I 
suppose there could be one in the future that has 3 but can't probe it.

TBH the main reason I added it was because it was confusing to work out 
what the actual max was. This says 2 when in reality it's 3. I suppose 
documenting that it should be left blank if reading from the hardware is 
supported might improve it too.

> > Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
> > ---
> >   Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml
> > index a65a42ccaafe..ce7bd44ee17e 100644
> > --- a/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml
> > +++ b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml
> > @@ -64,7 +64,7 @@ properties:
> >       description:
> >         number of chip selects.
> >       minimum: 1
> > -    maximum: 2
> > +    maximum: 3
> >       default: 1
> >   
> >     power-domains:
> >
> > --
> > 2.34.1