linux-kernel - Re: [PATCH 1/5] dt-bindings: media: venus: Add qcm2290 dt schema

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Message-ID: <aFBNVjl4n7I+OkO5@trex>
Date: Mon, 16 Jun 2025 18:59:02 +0200
From: Jorge Ramirez <jorge.ramirez@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Jorge Ramirez <jorge.ramirez@....qualcomm.com>, quic_vgarodia@...cinc.com,
        quic_dikshita@...cinc.com, bryan.odonoghue@...aro.org,
        mchehab@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, stanimir.varbanov@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] dt-bindings: media: venus: Add qcm2290 dt schema

On 16/06/25 18:23:18, Krzysztof Kozlowski wrote:
> On 16/06/2025 18:18, Jorge Ramirez wrote:
> > On 16/06/25 16:41:44, Krzysztof Kozlowski wrote:
> >> On 16/06/2025 14:52, Jorge Ramirez wrote:
> >>>>
> >>>>> +  The Venus AR50_LITE IP is a video encode and decode accelerator present
> >>>>> +  on Qualcomm platforms
> >>>>> +
> >>>>> +allOf:
> >>>>> +  - $ref: qcom,venus-common.yaml#
> >>>>> +
> >>>>> +properties:
> >>>>> +  compatible:
> >>>>> +    const: qcom,qcm2290-venus
> >>>>> +
> >>>>> +  power-domains:
> >>>>> +    minItems: 2
> >>>>> +    maxItems: 3
> >>>>> +
> >>>>> +  power-domain-names:
> >>>>> +    minItems: 2
> >>>>
> >>>> Why is this flexible? Either you have two or three. Not mixed.
> >>>
> >>> please check 5b380f242f360256c96e96adabeb7ce9ec784306
> >>
> >> This does not explain why this is optional HERE. You cannot use for a
> >> new platform an argument that some existing platform was changed in
> >> ABI-preserving way.
> > 
> > thanks for quick the follow up.
> > 
> > but bear with me please because I dont follow - why can the same logic
> > be used - it being applicable - and therefore result in a definition
> > similar to those other platforms?
> 
> Because this platform either has 2 or 3, not both. Unless that's not
> true, but then please share some arguments.

as with every other venus schema with more than 1 power domain, the
argument is the same one that I have shared with you a couple of
messages back (DVFS).

verbatim:
    Venus needs to vote for the performance state of a power domain (cx)
    to be able to support DVFS. This 'cx' power domain is controlled by
    rpm and is a common power domain (scalable) not specific to
    venus alone. This is optional in the sense that, leaving this power
    domain out does not really impact the functionality but just makes
    the platform a little less power efficient.

Seeing all these venus schemas follow the same pattern, it seems to me
that this is the correct way of implementing the above.

You seem to disagree. please could you explain?

> 
> Best regards,
> Krzysztof