RE: [PATCH v16 4/5] dt-bindings: remoteproc: Add documentation for ZynqMP R5 rproc bindings

[Ben Levinsky]

Hi Rob,

> -----Original Message-----
> From: Rob Herring <robh@xxxxxxxxxx>
> Sent: Tuesday, September 29, 2020 11:36 AM
> To: Ben Levinsky <BLEVINSK@xxxxxxxxxx>
> Cc: Stefano Stabellini <stefanos@xxxxxxxxxx>; Michal Simek
> <michals@xxxxxxxxxx>; michael.auchter@xxxxxx; devicetree@xxxxxxxxxxxxxxx;
> mathieu.poirier@xxxxxxxxxx; Ed T. Mooring <emooring@xxxxxxxxxx>; linux-
> remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; Jason Wu <j.wu@xxxxxxxxxx>; Jiaying Liang
> <jliang@xxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>
> Subject: Re: [PATCH v16 4/5] dt-bindings: remoteproc: Add documentation for
> ZynqMP R5 rproc bindings
> 
> On Tue, Sep 22, 2020 at 03:39:29PM -0700, Ben Levinsky wrote:
> > Add binding for ZynqMP R5 OpenAMP.
> >
> > Represent the RPU domain resources in one device node. Each RPU
> > processor is a subnode of the top RPU domain node.
> >
> > Signed-off-by: Jason Wu <j.wu@xxxxxxxxxx>
> > Signed-off-by: Wendy Liang <jliang@xxxxxxxxxx>
> > Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
> > Signed-off-by: Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> > ---
> > v3:
> > - update zynqmp_r5 yaml parsing to not raise warnings for extra
> >   information in children of R5 node. The warning "node has a unit
> >   name, but no reg or ranges property" will still be raised though
> >   as this particular node is needed to describe the
> >   '#address-cells' and '#size-cells' information.
> > v4::
> > - remove warning '/example-0/rpu@ff9a0000/r5@0:
> >   node has a unit name, but no reg or ranges property'
> >   by adding reg to r5 node.
> > v5:
> > - update device tree sample and yaml parsing to not raise any warnings
> > - description for memory-region in yaml parsing
> > - compatible string in yaml parsing for TCM
> > v6:
> > - remove coupling TCM nodes with remoteproc
> > - remove mailbox as it is optional not needed
> > v7:
> > - change lockstep-mode to xlnx,cluster-mode
> > v9:
> > - show example IPC nodes and tcm bank nodes
> > v11:
> > - add property meta-memory-regions to illustrate link
> >   between r5 and TCM banks
> > - update so no warnings from 'make dt_binding_check'
> > v14:
> > - concerns were raised about the new property meta-memory-regions.
> >   There is no clear direction so for the moment I kept it in the series
> > - place IPC nodes in RAM in the reserved memory section
> > v15:
> > - change lockstep-mode prop as follows: if present, then RPU cluster is in
> >   lockstep mode. if not present, cluster is in split mode.
> > ---
> >  .../xilinx,zynqmp-r5-remoteproc.yaml          | 120 ++++++++++++++++++
> >  1 file changed, 120 insertions(+)
> >  create mode 100644
> Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> remoteproc.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-
> r5-remoteproc.yaml
> b/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> remoteproc.yaml
> > new file mode 100644
> > index 000000000000..ce02e425692e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/remoteproc/xilinx,zynqmp-r5-
> remoteproc.yaml
> > @@ -0,0 +1,120 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: "http://devicetree.org/schemas/remoteproc/xilinx,zynqmp-r5-
> remoteproc.yaml#"
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#";
> > +
> > +title: Xilinx R5 remote processor controller bindings
> > +
> > +description:
> > +  This document defines the binding for the remoteproc component that
> loads and
> > +  boots firmwares on the Xilinx Zynqmp and Versal family chipset.
> > +
> > +  Note that the Linux has global addressing view of the R5-related memory
> (TCM)
> > +  so the absolute address ranges are provided in TCM reg's.
> 
> blank line needed.
> 
will fix in next rev.
> TCMs specifically I'm concerned about how they are represented in system
> DT and here...
> 
So System DT can tie in with lopper plugin/assists so that TCMs are output to whatever the linux driver expects. 
> > +maintainers:
> > +  - Ed Mooring <ed.mooring@xxxxxxxxxx>
> > +  - Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> > +
> > +properties:
> > +  compatible:
> > +    const: "xlnx,zynqmp-r5-remoteproc-1.0"
> 
> Don't need quotes.
> 
will fix in next rev.
> The use of version numbers was allowed for Xilinx programmable IP. I
> don't think this falls into that category.
> 
will fix in next rev.
> > +
> > +  lockstep-mode:
> > +    description:
> > +      If this property is present, then the configuration is lock-step.
> 
> boolean...
> 
By this comment do you mean you want this to change or mention that it is implicitly Boolean?
> > +      Otherwise RPU is split.
> > +    maxItems: 1
> 
> ...or an array?
> 
> Either way, doesn't work for TI R5.
> 
So as the configuration for both the TI R5 and Xilinx R5 is independent what in common would you like to see here?
For example Xilinx driver can similarly have the "Xilinx,cluster-mode" or "cluster-mode" but for Xilinx platform manager our split configuration value in Xilinx platform manager is '0' while in TI drver it is '1'. So I can make the driver expect it then translate if needed if this what you prefer. 

Otherwise how would  you suggest the Xilinx r5 remoteproc driver describe split/lockstep mode?
> > +
> > +  interrupts:
> > +    description:
> > +      Interrupt mapping for remoteproc IPI. It is required if the
> > +      user uses the remoteproc driver with the RPMsg kernel driver.
> > +    maxItems: 6
> > +
> > +  memory-region:
> > +    description:
> > +      collection of memory carveouts used for elf-loading and inter-processor
> > +      communication.
> > +    maxItems: 4
> > +    minItems: 4
> 
> Need to define what each region is.
> 
> One blank line between properties.
> 
will fix in next rev. for memory-regions is the following ok?
      collection of phandles for memory carveouts for elf-loading and
       inter-processor communication.

       This collection can consist of reserved-mem carveouts in DDR.

> > +  meta-memory-regions:
> > +    description:
> > +      collection of memories that are not present in the top level memory
> > +      nodes' mapping. For example, R5s' TCM banks. These banks are needed
> > +      for R5 firmware meta data such as the R5 firmware's heap and stack
> 
> Humm, needs a better explanation.
How is the following:
Collection of phandles for reserved on-chip SRAM regions.


Otherwise I can get rid of this property and combine into memory-region if you wish.

> 
> > +  pnode-id:
> > +    maxItems: 1
> 
> What's this?
> 
Can add the following:
power node id that is used to uniquely identify the RPU for Xilinx
      Power Management. The value is then passed to Xilinx platform
      manager for power on/off and access.
> > +  mboxes:
> > +    maxItems: 2
> 
> Need to define what each one is.
> 
How is the following:
array of phandles that describe the rx and tx for xilinx zynqmp
      mailbox driver. order of rx and tx is described by the mbox-names
      property. This will be used for communication with remote
      processor.
> > +  mbox-names:
> > +    maxItems: 2
> 
> Need to define the names.
> 
How is the following:
array of strings that denote which item in the mboxes property array
      are the rx and tx for xilinx zynqmp mailbox driver
> > +
> > +examples:
> > +  - |
> > +     reserved-memory {
> > +          #address-cells = <1>;
> > +          #size-cells = <1>;
> > +          ranges;
> > +          elf_load: rproc@3ed000000 {
> > +               no-map;
> > +               reg = <0x3ed00000 0x40000>;
> > +          };
> > +
> > +          rpu0vdev0vring0: rpu0vdev0vring0@3ed40000 {
> > +               no-map;
> > +               reg = <0x3ed40000 0x4000>;
> > +          };
> > +          rpu0vdev0vring1: rpu0vdev0vring1@3ed44000 {
> > +               no-map;
> > +               reg = <0x3ed44000 0x4000>;
> > +          };
> > +          rpu0vdev0buffer: rpu0vdev0buffer@3ed48000 {
> > +               no-map;
> > +               reg = <0x3ed48000 0x100000>;
> > +          };
> > +
> > +     };
> > +
> > +     /*
> > +      * Below nodes are required if using TCM to load R5 firmware
> > +      * if not, then either do not provide nodes are label as disabled in
> > +      * status property
> > +      */
> > +     tcm0a: tcm_0a@ffe00000 {
> > +         reg = <0xffe00000 0x10000>;
> > +         pnode-id = <0xf>;
> > +         no-map;
> > +         status = "okay";
> > +         phandle = <0x40>;
> > +         compatible = "xlnx,tcm";
> 
> TCM is a Xilinx specific thing?
> 
No... good point. Can remove the compatible string in next rev.
> > +     };
> > +     tcm0b: tcm_1a@ffe20000 {
> > +         reg = <0xffe20000 0x10000>;
> > +         pnode-id = <0x10>;
> > +         no-map;
> > +         status = "okay";
> > +         compatible = "xlnx,tcm";
> > +         phandle = <0x41>;
> > +     };
> > +
> > +     rpu {
> > +          compatible = "xlnx,zynqmp-r5-remoteproc-1.0";
> > +          #address-cells = <1>;
> > +          #size-cells = <1>;
> > +          ranges;
> > +          lockstep-mode;
> > +          r5_0 {
> > +               ranges;
> > +               #address-cells = <1>;
> > +               #size-cells = <1>;
> > +               memory-region = <&elf_load>,
> > +                               <&rpu0vdev0vring0>,
> > +                               <&rpu0vdev0vring1>,
> > +                               <&rpu0vdev0buffer>;
> > +               meta-memory-regions = <&tcm_0a>, <&tcm_0b>;
> > +               pnode-id = <0x7>;
> > +          };
> > +     };
> > +
> > +...
> > --
> > 2.17.1
> >
Thank you,
Ben