Re: [PATCH v5 2/3] dt-bindings: mfd: aspeed,ast2x00-scu: Describe AST2700 SCU0

[Rob Herring <robh@kernel.org>]

On Thu, Apr 02, 2026 at 06:14:06AM +0000, Billy Tsai wrote:
> > > AST2700 consists of two interconnected SoC instances, each with its own
> > > System Control Unit (SCU). The SCU0 provides pin control, interrupt
> > > controllers, clocks, resets, and address-space mappings for the
> > > Secondary and Tertiary Service Processors (SSP and TSP).
> > >
> > > Describe the SSP/TSP address mappings using the standard
> > > memory-region and memory-region-names properties.
> > >
> > > Disallow legacy child nodes that are not present on AST2700, including
> > > p2a-control and smp-memram. The latter is unnecessary as software can
> > > access the scratch registers via the SCU syscon.
> > >
> > > Also allow the AST2700 SoC0 pin controller to be described as a child
> > > node of the SCU0, and add an example illustrating the SCU0 layout,
> > > including reserved-memory, interrupt controllers, and pinctrl.
> > >
> > > Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
> > > ---
> > >  .../bindings/mfd/aspeed,ast2x00-scu.yaml           | 117 +++++++++++++++++++++
> > >  1 file changed, 117 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/mfd/aspeed,ast2x00-scu.yaml b/Documentation/devicetree/bindings/mfd/aspeed,ast2x00-scu.yaml
> > > index a87f31fce019..86d51389689c 100644
> > > --- a/Documentation/devicetree/bindings/mfd/aspeed,ast2x00-scu.yaml
> > > +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2x00-scu.yaml
> > > @@ -46,6 +46,9 @@ properties:
> > >    '#reset-cells':
> > >      const: 1
> > >
> > > +  memory-region: true
> > > +  memory-region-names: true
> 
> > Missing constraints. From where did you take such syntax (so I can fix
> > it)?
> 
> The intention was to constrain these properties conditionally for
> AST2700 SCU0 as done further down in the patch.
> 
> I can update the binding so that memory-region and memory-region-names
> have baseline constraints (e.g. minItems and maxItems), and then refine them in the
> conditional branches for AST2700SCU0, AST2700SCU1 and others
> 
>   memory-region:
>     minItems: 2
>     maxItems: 3
>   memory-region-names:
>     minItems: 2
>     maxItems: 3

As of this patch, you don't need that. You can just define the regions 
and names at the top-level. And the conditional schema only needs to 
disallow them for the appropriate case.

Rob