Re: [PATCH v3 1/6] dt-bindings: crypto: Document support for SPAcc

[Krzysztof Kozlowski <krzk@kernel.org>]

On 06/06/2025 13:02, Pavitrakumar Managutte wrote:
> Hi Krzysztof,
>   Appreciate your inputs and feedback. My comments are embedded below.
> 
> Warm regards,
> PK
> 
> On Wed, Jun 4, 2025 at 7:37 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 04/06/2025 14:20, Pavitrakumar Managutte wrote:
>>>>
>>>>>>> +
>>>>>>> +  snps,vspacc-id:
>>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>>>> +    description: |
>>>>>>> +      Virtual SPAcc instance identifier.
>>>>>>> +      The SPAcc hardware supports multiple virtual instances (determined by
>>>>>>> +      ELP_SPACC_CONFIG_VSPACC_CNT parameter), and this ID is used to identify
>>>>>>> +      which virtual instance this node represents.
>>>>>>
>>>>>> No, IDs are not accepted.
>>>>>
>>>>> PK: This represents the specific virtual SPAcc that is being used in
>>>>> the current configuration. It is used to index into the register banks
>>>>> and the context memories of the virtual SPAcc that is being used. The
>>>>> SPAcc IP can be configured as dedicated virtual SPAccs in
>>>>> heterogeneous environments.
>>>>
>>>> OK. Why registers are not narrowed to only this instance? It feels like
>>>> you provide here full register space for multiple devices and then
>>>> select the bank with above ID.
>>>
>>> PK: No, we cant narrow the registers to only this instance since its
>>> is just a single SPAcc with multiple virtual SPAcc instances. The same
>>> set of registers(aka register banks) and context memories are
>>> repeated, but sit at different offset addresses (i*4000 +
>>> register-offsets). The crypto hardware engine inside is shared by all
>>> the virtual SPAccs. This is very much for a heterogeneous computing
>>> scenario.
>>
>> Then maybe you have one crypto engine? You ask us to guess all of this,
>> also because you do not upstream the DTS for real product. Any
>> mentioning of "virtual" already raises concerns...
> 
> PK: Yes this is a single crypto engine, maybe I should have detailed
> that in the cover letter. I will fix that. And what I have pushed in

So one node, thus no need for this entire virtual device split.

> the patch is my complete DTS. It might need updating depending on the

If this is complete, then obviously "snps,vspacc-id" is not necessary.


Best regards,
Krzysztof