Re: [PATCH v4 1/3] dt-bindings: edac: xlnx,versal-ddrmc: Add xlnx,versal-xilsem compatible

[Yazen Ghannam]

On Thu, Oct 22, 2026 at 09:37:30AM -0500, Rob Herring wrote:
> On Wed, Oct 21, 2026 at 06:27:20PM +0530, Rama devi Veggalam wrote:
> > Add the "xlnx,versal-xilsem" compatible string for the Versal
> > XilSEM (Xilinx Soft Error Mitigation) hardware block.
> > 
> > XilSEM runs as part of the Platform Loader and Manager (PLM) on the
> > PMC and detects (and optionally corrects) soft errors in Versal
> > Configuration Memory, notifying error events to user applications.
> > 
> > The new compatible string only needs a single register region and
> > does not use reg-names or interrupts, so the schema gates these
> > requirements per compatible string.
> > 
> > Signed-off-by: Rama devi Veggalam <rama.devi.veggalam@xxxxxxx>
> > ---
> > Changes in v4:
> > - Added a new "xlnx,versal-xilsem" compatible string to the existing
> >   xlnx,versal-ddrmc-edac.yaml binding, gated via allOf/if-then so
> >   DDRMC and XilSEM requirements (reg, reg-names, interrupts) are
> >   validated independently per compatible string.
> > 
> > Changes in v3:
> > - Merged XilSEM edac with Versal Edac
> > 
> > Changes in v2:
> > - Changed "xlnx,versal-xilsem-edac" to constant
> > - Removed "compatible: in required section
> > - Removed "|" in description
> > - Removed "items" in compatible
> > - Fixed indentation in examples
> > - Updated title and description
> > ---
> >  .../memory-controllers/xlnx,versal-ddrmc-edac.yaml | 64 +++++++++++++++++++---
> >  1 file changed, 57 insertions(+), 7 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/memory-controllers/xlnx,versal-ddrmc-edac.yaml b/Documentation/devicetree/bindings/memory-controllers/xlnx,versal-ddrmc-edac.yaml
> > index 12f8e9f..b5dc320 100644
> > --- a/Documentation/devicetree/bindings/memory-controllers/xlnx,versal-ddrmc-edac.yaml
> > +++ b/Documentation/devicetree/bindings/memory-controllers/xlnx,versal-ddrmc-edac.yaml
> > @@ -4,25 +4,35 @@
> >  $id: http://devicetree.org/schemas/memory-controllers/xlnx,versal-ddrmc-edac.yaml#
> >  $schema: http://devicetree.org/meta-schemas/core.yaml#
> >  
> > -title: Xilinx Versal DDRMC (Integrated DDR Memory Controller)
> > +title: Xilinx Versal DDRMC (Integrated DDR Memory Controller) and XilSEM EDAC
> >  
> >  maintainers:
> >    - Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxx>
> >    - Sai Krishna Potthuri <sai.krishna.potthuri@xxxxxxx>
> > +  - Rama Devi Veggalam <rama.devi.veggalam@xxxxxxx>
> >  
> >  description:
> >    The integrated DDR Memory Controllers (DDRMCs) support both DDR4 and LPDDR4/
> >    4X memory interfaces. Versal DDR memory controller has an optional ECC support
> >    which correct single bit ECC errors and detect double bit ECC errors.
> >  
> > +  Xilinx Versal Soft Error Mitigation (XilSEM) is part of the Platform Loader
> > +  and Manager (PLM) which is loaded into and runs on the Platform Management
> > +  Controller (PMC). XilSEM is responsible for detecting and optionally
> > +  correcting soft errors in Configuration Memory of Versal. Whenever an error
> > +  is detected, be it correctable or uncorrectable, XilSEM notifies the errors
> > +  to user applications via the firmware's event notification interface,
> > +  rather than a devicetree-described interrupt.
> > +
> >  properties:
> >    compatible:
> > -    const: xlnx,versal-ddrmc
> > +    enum:
> > +      - xlnx,versal-ddrmc
> > +      - xlnx,versal-xilsem
> >  
> >    reg:
> > -    items:
> > -      - description: DDR Memory Controller registers
> > -      - description: NOC registers corresponding to DDR Memory Controller
> > +    minItems: 1
> > +    maxItems: 2
> >  
> >    reg-names:
> >      items:
> > @@ -35,8 +45,39 @@ properties:
> >  required:
> >    - compatible
> >    - reg
> > -  - reg-names
> > -  - interrupts
> > +
> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: xlnx,versal-ddrmc
> > +    then:
> > +      properties:
> > +        reg:
> > +          items:
> > +            - description: DDR Memory Controller registers
> > +            - description: NOC registers corresponding to DDR Memory Controller
> > +        reg-names:
> > +          items:
> > +            - const: base
> > +            - const: noc
> > +      required:
> > +        - reg-names
> > +        - interrupts
> > +
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: xlnx,versal-xilsem
> > +    then:
> > +      properties:
> > +        reg:
> > +          items:
> > +            - description: XilSEM (Soft Error Mitigation) register region
> > +        reg-names: false
> > +        interrupts: false
> 
> These 2 devices have absolutely 0 properties in common. It makes no 
> sense to share a binding doc.
> 

Right, and maybe DT isn't needed at all?

One option in the Sashiko feedback is to use a platform driver.

IIUC, here's a summary:
1) Drop this DT patch.
2) Have ZYNQMP_FIRMWARE create a platform driver for XilSEM.
3) Have the Versal EDAC module use the XilSEM platform driver.

Rama, what do you think?

Thanks,
Yazen