Re: [PATCH v6 1/6] dt-bindings: remoteproc: Add Xilinx RPU subsystem bindings

[Rob Herring]

On Wed, Jun 01, 2022 at 12:05:09PM -0700, Tanmay Shah wrote:
> Hi Rob,
> 
> Thanks for reviews. Please find my comments below:
> 
> On 6/1/22 11:42 AM, Rob Herring wrote:
> > On Tue, May 31, 2022 at 04:43:05PM -0700, Tanmay Shah wrote:
> > > Xilinx ZynqMP platform has dual-core ARM Cortex R5 Realtime Processing
> > > Unit(RPU) subsystem. This patch adds dt-bindings for RPU subsystem
> > > (cluster).
> > > 
> > > Signed-off-by: Tanmay Shah <tanmay.shah@xxxxxxxxxx>
> > > ---
> > > 
> > > Changes in v6:
> > >    - Add maxItems to sram and memory-region property
> > > 
> > > Changes in v5:
> > > - Add constraints of the possible values of xlnx,cluster-mode property
> > > - fix description of power-domains property for r5 core
> > > - Remove reg, address-cells and size-cells properties as it is not required
> > > - Fix description of mboxes property
> > > - Add description of each memory-region and remove old .txt binding link
> > >    reference in the description
> > > 
> > > Changes in v4:
> > >    - Add memory-region, mboxes and mbox-names properties in example
> > > 
> > > Changes in v3:
> > >    - None
> > > 
> > > 
> > >   .../bindings/remoteproc/xlnx,r5f-rproc.yaml   | 129 ++++++++++++++++++
> > >   include/dt-bindings/power/xlnx-zynqmp-power.h |   6 +
> > >   2 files changed, 135 insertions(+)
> > >   create mode 100644 Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> > > new file mode 100644
> > > index 000000000000..cbff1c201a89
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> > > @@ -0,0 +1,129 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/remoteproc/xlnx,r5f-rproc.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Xilinx R5F processor subsystem
> > > +
> > > +maintainers:
> > > +  - Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> > > +  - Tanmay Shah <tanmay.shah@xxxxxxxxxx>
> > > +
> > > +description: |
> > > +  The Xilinx platforms include a pair of Cortex-R5F processors (RPU) for
> > > +  real-time processing based on the Cortex-R5F processor core from ARM.
> > > +  The Cortex-R5F processor implements the Arm v7-R architecture and includes a
> > > +  floating-point unit that implements the Arm VFPv3 instruction set.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: xlnx,zynqmp-r5fss
> > > +
> > > +  xlnx,cluster-mode:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    enum: [0, 1, 2]
> > > +    description: |
> > > +      The RPU MPCore can operate in split mode(Dual-processor performance), Safety
> > > +      lock-step mode(Both RPU cores execute the same code in lock-step,
> > > +      clock-for-clock) or Single CPU mode (RPU core 0 can be held in reset while
> > > +      core 1 runs normally). The processor does not support dynamic configuration.
> > > +      Switching between modes is only permitted immediately after a processor reset.
> > > +      If set to  1 then lockstep mode and if 0 then split mode.
> > > +      If set to  2 then single CPU mode. When not defined, default will be lockstep mode.
> > > +
> > > +patternProperties:
> > > +  "^r5f-[a-f0-9]+$":
> > > +    type: object
> > > +    description: |
> > > +      The RPU is located in the Low Power Domain of the Processor Subsystem.
> > > +      Each processor includes separate L1 instruction and data caches and
> > > +      tightly coupled memories (TCM). System memory is cacheable, but the TCM
> > > +      memory space is non-cacheable.
> > > +
> > > +      Each RPU contains one 64KB memory and two 32KB memories that
> > > +      are accessed via the TCM A and B port interfaces, for a total of 128KB
> > > +      per processor. In lock-step mode, the processor has access to 256KB of
> > > +      TCM memory.
> > > +
> > > +    properties:
> > > +      compatible:
> > > +        const: xlnx,zynqmp-r5f
> > > +
> > > +      power-domains:
> > > +        description: RPU core PM domain specifier
> > > +        maxItems: 1
> > > +
> > > +      mboxes:
> > > +        minItems: 1
> > > +        items:
> > > +          - description: mailbox channel to send data to RPU
> > > +          - description: mailbox channel to receive data from RPU
> > > +
> > > +      mbox-names:
> > > +        minItems: 1
> > > +        items:
> > > +          - const: tx
> > > +          - const: rx
> > > +
> > > +      sram:
> > > +        $ref: /schemas/types.yaml#/definitions/phandle-array
> > > +        maxItems: 8
> > minItems: 1
> > maxItems: 8
> > items:
> >    maxItems: 1
> 
> I have posted v7 which adds "minItems: 1".
> 
> However, I didn't get items: part. Is it required to have items: now?

Yes.
> 
> Can I add items: part once TCM bindings are posted?

No.

> I understand that minItems and maxItems under sram property decides how many
> phandles sram can have.
> 
> However, maxItems: 1 under items: field what it describes?

'phandle-array' is really a matrix type because we can have phandles 
plus argument cells. So you have to define each of the 1-8 entries is a 
single phandle cell (and no arg cells).

Rob