Re: [PATCH v12 2/4] dt-bindings: remoteproc: add Tightly Coupled Memory (TCM) bindings

[Tanmay Shah <tanmay.shah@amd.com>]

Hello Krzysztof,

Thanks for reviews. Please find my comments below.

On 3/9/24 7:25 AM, Krzysztof Kozlowski wrote:
> On 01/03/2024 19:16, Tanmay Shah wrote:
> > From: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
> > 
> > Introduce bindings for TCM memory address space on AMD-xilinx Zynq
> > UltraScale+ platform. It will help in defining TCM in device-tree
> > and make it's access platform agnostic and data-driven.
> > 
> > Tightly-coupled memories(TCMs) are low-latency memory that provides
> > predictable instruction execution and predictable data load/store
> > timing. Each Cortex-R5F processor contains two 64-bit wide 64 KB memory
> > banks on the ATCM and BTCM ports, for a total of 128 KB of memory.
> > 
> > The TCM resources(reg, reg-names and power-domain) are documented for
> > each TCM in the R5 node. The reg and reg-names are made as required
> > properties as we don't want to hardcode TCM addresses for future
> > platforms and for zu+ legacy implementation will ensure that the
> > old dts w/o reg/reg-names works and stable ABI is maintained.
> > 
> > It also extends the examples for TCM split and lockstep modes.
> > 
> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
> > Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
> > ---
> > 
> > Changes in v12:
> >   - add "reg", "reg-names" and "power-domains" in pattern properties
> >   - add "reg" and "reg-names" in required list
> >   - keep "power-domains" in required list as it was before the change
> > 
> > Changes in v11:
> >   - Fix yamllint warning and reduce indentation as needed
> > 
> >  .../remoteproc/xlnx,zynqmp-r5fss.yaml         | 188 ++++++++++++++++--
> >  1 file changed, 168 insertions(+), 20 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml b/Documentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml
> > index 78aac69f1060..dc6ce308688f 100644
> > --- a/Documentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml
> > +++ b/Documentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml
> > @@ -20,9 +20,21 @@ properties:
> >    compatible:
> >      const: xlnx,zynqmp-r5fss
> >  
> > +  "#address-cells":
> > +    const: 2
> > +
> > +  "#size-cells":
> > +    const: 2
> > +
> > +  ranges:
> > +    description: |
> > +      Standard ranges definition providing address translations for
> > +      local R5F TCM address spaces to bus addresses.
> > +
> >    xlnx,cluster-mode:
> >      $ref: /schemas/types.yaml#/definitions/uint32
> >      enum: [0, 1, 2]
> > +    default: 1
> >      description: |
> >        The RPU MPCore can operate in split mode (Dual-processor performance), Safety
> >        lock-step mode(Both RPU cores execute the same code in lock-step,
> > @@ -37,7 +49,7 @@ properties:
> >        2: single cpu mode
> >  
> >  patternProperties:
> > -  "^r5f-[a-f0-9]+$":
> > +  "^r5f@[0-9a-f]+$":
> >      type: object
> >      description: |
> >        The RPU is located in the Low Power Domain of the Processor Subsystem.
> > @@ -54,8 +66,17 @@ patternProperties:
> >        compatible:
> >          const: xlnx,zynqmp-r5f
> >  
> > +      reg:
> > +        minItems: 1
> > +        maxItems: 4
> > +
> > +      reg-names:
> > +        minItems: 1
> > +        maxItems: 4
> > +
> >        power-domains:
> > -        maxItems: 1
> > +        minItems: 2
> > +        maxItems: 5
> >  
> >        mboxes:
> >          minItems: 1
> > @@ -101,35 +122,162 @@ patternProperties:
> >  
> >      required:
> >        - compatible
> > +      - reg
> > +      - reg-names
> >        - power-domains
> >  
> > -    unevaluatedProperties: false
> > -
> >  required:
> >    - compatible
> > +  - "#address-cells"
> > +  - "#size-cells"
> > +  - ranges
> > +
> > +allOf:
> > +  - if:
> > +      properties:
> > +        xlnx,cluster-mode:
> > +          enum:
> > +            - 1
> > +    then:
> > +      patternProperties:
> > +        "^r5f@[0-9a-f]+$":
> > +          type: object
> > +
> > +          properties:
> > +            reg:
> > +              minItems: 1
> > +              items:
> > +                - description: ATCM internal memory
> > +                - description: BTCM internal memory
> > +                - description: extra ATCM memory in lockstep mode
> > +                - description: extra BTCM memory in lockstep mode
> > +
> > +            reg-names:
> > +              minItems: 1
> > +              items:
> > +                - const: atcm0
> > +                - const: btcm0
> > +                - const: atcm1
> > +                - const: btcm1
>
> Why power domains are flexible?

User may not want to use all the TCMs. For example, if users want to turn-on only TCM-A and rest of them want to keep off, then

they can avoid having power-domains of other TCMs in the device-tree. This helps with less power-consumption when needed.

Hence flexible list of power-domains list.

I can certainly mention "items:" under power-domains property.


>
> > +
> > +    else:
> > +      patternProperties:
> > +        "^r5f@[0-9a-f]+$":
> > +          type: object
> > +
> > +          properties:
> > +            reg:
> > +              minItems: 1
> > +              items:
> > +                - description: ATCM internal memory
> > +                - description: BTCM internal memory
> > +
> > +            reg-names:
> > +              minItems: 1
> > +              items:
> > +                - const: atcm0
> > +                - const: btcm0
> > +
> > +            power-domains:
> > +              maxItems: 3
>
> Please list power domains.

Okay. But minItems will be still what's mentioned above i.e. 2.

I hope it's fine.


>
> >  
> >  additionalProperties: false
>
>
> Best regards,
> Krzysztof
>