Re: [PATCH v2 1/2] dt-bindings: remoteproc: document AMD BRAM-based rproc

[Michal Simek <michal.simek@amd.com>]

On 4/28/26 15:12, Krzysztof Kozlowski wrote:
> On 28/04/2026 15:09, Michal Simek wrote:
>>
>>
>> On 4/28/26 11:14, Krzysztof Kozlowski wrote:
>>> On 28/04/2026 11:04, Michal Simek wrote:
>>>>
>>>>
>>>> On 4/28/26 10:47, Krzysztof Kozlowski wrote:
>>>>> On 28/04/2026 10:33, Michal Simek wrote:
>>>>>>
>>>>>>
>>>>>> On 4/28/26 08:50, Krzysztof Kozlowski wrote:
>>>>>>> On Mon, Apr 27, 2026 at 09:27:02AM -0700, Ben Levinsky wrote:
>>>>>>>> Describe an AMD BRAM-based soft-core processor subsystem instantiated in
>>>>>>>> programmable logic and using dual-port BRAM for firmware storage and
>>>>>>>> execution.
>>>>>>>>
>>>>>>>> The binding models a soft-core processor subsystem instantiated in AMD
>>>>>>>> programmable logic and using dual-port BRAM for firmware storage and
>>>>>>>> execution. The remoteproc device is represented as a child node whose
>>>>>>>> reg property describes the firmware memory window in the processor-local
>>>>>>>> address space. The parent bus node provides standard devicetree address
>>>>>>>> translation through ranges so Linux can access the same BRAM through the
>>>>>>>> system physical address space.
>>>>>>>>
>>>>>>>> A clock input feeds the soft-core processor subsystem, and an active-low
>>>>>>>> reset GPIO holds the processor in reset until firmware loading
>>>>>>>> completes. The firmware-name property is optional.
>>>>>>>>
>>>>>>>> Signed-off-by: Ben Levinsky <ben.levinsky@amd.com>
>>>>>>>> ---
>>>>>>>>      .../bindings/remoteproc/amd,bram-rproc.yaml   | 98 +++++++++++++++++++
>>>>>>>>      1 file changed, 98 insertions(+)
>>>>>>>>      create mode 100644 Documentation/devicetree/bindings/remoteproc/amd,bram-rproc.yaml
>>>>>>>>
>>>>>>>> diff --git a/Documentation/devicetree/bindings/remoteproc/amd,bram-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/amd,bram-rproc.yaml
>>>>>>>> new file mode 100644
>>>>>>>> index 000000000000..f16657dc0d9f
>>>>>>>> --- /dev/null
>>>>>>>> +++ b/Documentation/devicetree/bindings/remoteproc/amd,bram-rproc.yaml
>>>>>>>> @@ -0,0 +1,98 @@
>>>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>>>>> +%YAML 1.2
>>>>>>>> +---
>>>>>>>> +$id: http://devicetree.org/schemas/remoteproc/amd,bram-rproc.yaml#
>>>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>>>> +
>>>>>>>> +title: AMD BRAM-based Remote Processor
>>>>>>>> +
>>>>>>>> +maintainers:
>>>>>>>> +  - Ben Levinsky <ben.levinsky@amd.com>
>>>>>>>> +
>>>>>>>> +description: |
>>>>>>>> +  Soft-core processor subsystem instantiated in AMD programmable logic and
>>>>>>>> +  using dual-port BRAM for firmware storage and execution.
>>>>>>>
>>>>>>> Isn't the soft-core or FPGA still part of some Xilinx SoC? Or is this
>>>>>>> completely different thing from SoC and there is a design WITHOUT SoC
>>>>>>> using this remote proc?
>>>>>>
>>>>>> In 99% case this is going to be used on Xilinx SOC with programmable logic next
>>>>>> to ARM core.
>>>>>> soft core means - means VHDL/Verilog code synthesized to programmable
>>>>>> logic/fpga. It means exact location in chip varies based on build and constraints.
>>>>>>
>>>>>> hard core - physical HW location - like ARM cores in our chip.
>>>>>>
>>>>>> (ARM is providing RTL/code that even ARM cores in fpga emulated platforms are
>>>>>> actually used as soft cores).
>>>>>>
>>>>>> Not sure if you want me to talk about that 1% use cases which are also possible
>>>>>> but don't think anybody will design them.
>>>>>
>>>>> Then I would treat it exactly like every other block of a SoC - you need
>>>>> a SoC specific compatible. If there is a fallback, SoC specific
>>>>> compatible should be used in the fallback as well - that's all already
>>>>> documented in writing-bindings.
>>>>
>>>> But which SOC? We have ZynqMP, Versal, Versal NET, Versal Gen 2. And all of
>>>> these will use this configuration.
>>>> Do you want to list all of them?
>>>
>>> "Then I would treat it exactly like every other block of a SoC"
>>
>> No issue. Here is snippet.
>>
>>     properties:
>>       compatible:
>>         items:
>>           - enum:
>>               - xlnx,zynqmp-bram-rproc
>>               - xlnx,versal-bram-rproc
>>               - xlnx,versal-net-bram-rproc
>>               - amd,versal2-bram-rproc
>>           - const: amd,bram-rproc
>>
>>     The example should also be updated:
> 
> Yes, except what I wrote earlier and is mentioned in the writing
> bindings doc - the specific compatible should be also the fallback.

   properties:
     compatible:
       oneOf:
         - const: xlnx,zynqmp-bram-rproc
         - items:
             - enum:
                 - xlnx,versal-bram-rproc
                 - xlnx,versal-net-bram-rproc
                 - amd,versal2-bram-rproc
             - const: xlnx,zynqmp-bram-rproc

Good now?

M