linux-kernel - Re: [PATCH v3 1/8] dt-bindings: clock: qcom: Allow VDD

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Date: Wed, 24 Jan 2024 13:21:16 -0800
From: Bjorn Andersson <quic_bjorande@...cinc.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        "Krzysztof
 Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Taniya Das <quic_tdas@...cinc.com>,
        Johan Hovold
	<johan+linaro@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/8] dt-bindings: clock: qcom: Allow VDD_GFX supply to
 GX

On Wed, Jan 24, 2024 at 07:31:34AM +0100, Krzysztof Kozlowski wrote:
> On 24/01/2024 05:25, Bjorn Andersson wrote:
> > +# Allow either power-domains or vdd-gfx-supply, not both
> > +oneOf:
> > +  - required:
> > +      - power-domains
> > +  - required:
> > +      - vdd-gfx-supply
> > +  - not:
> > +      anyOf:
> > +        - required:
> > +            - power-domains
> > +        - required:
> > +            - vdd-gfx-supply
> 
> I don't fully understand what you want to achieve here. If only "allow
> either", so not a "require either", then simpler:
> 
> https://lore.kernel.org/all/20230118163208.GA117919-robh@kernel.org/
> 

As discussed in v2, power-domains is currently an optional property in
this binding and I'm adding vdd-gfx-supply as an alternative to that.

As it's optional, barely any of our platforms define the property, so
requiring this would not be compatible with existing DT source.

It's clear that this does not accurately represent the power situation
for the block, so we should fix this. But I'd prefer to see that as a
separate task.

Implementation-wise, we need to figure how to consume multiple
power-domains in the GPUCC drivers in Linux, because the correct
definition seems to be to add both CX and GX/GFX domains here - and if
we just add them to the DT node Linux will break.

Regards,
Bjorn