linux-kernel - Re: [PATCH RFC 2/3] dt-bindings: opp: Add v2-qcom-adreno vendor bindings

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Message-ID: <20241015191314.pbz5v5u65gbpjheg@hu-akhilpo-hyd.qualcomm.com>
Date: Wed, 16 Oct 2024 00:43:14 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        "Konrad
 Dybcio" <konradybcio@...nel.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Marijn Suijten
	<marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, "Simona
 Vetter" <simona@...ll.ch>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon
	<nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH RFC 2/3] dt-bindings: opp: Add v2-qcom-adreno vendor
 bindings

On Mon, Oct 14, 2024 at 09:39:01AM +0200, Krzysztof Kozlowski wrote:
> On Sat, Oct 12, 2024 at 01:59:29AM +0530, Akhil P Oommen wrote:
> > Add a new schema which extends opp-v2 to support a new vendor specific
> > property required for Adreno GPUs found in Qualcomm's SoCs. The new
> > property called "qcom,opp-acd-level" carries a u32 value recommended
> > for each opp needs to be shared to GMU during runtime.
> > 
> > Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> > ---
> >  .../bindings/opp/opp-v2-qcom-adreno.yaml           | 84 ++++++++++++++++++++++
> >  1 file changed, 84 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/opp/opp-v2-qcom-adreno.yaml b/Documentation/devicetree/bindings/opp/opp-v2-qcom-adreno.yaml
> > new file mode 100644
> > index 000000000000..9fb828e9da86
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/opp/opp-v2-qcom-adreno.yaml
> > @@ -0,0 +1,84 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/opp/opp-v2-qcom-adreno.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Qualcomm Adreno compatible OPP supply
> > +
> > +description:
> > +  Adreno GPUs present in Qualcomm's Snapdragon chipsets uses an OPP specific
> > +  ACD related information tailored for the specific chipset. This binding
> > +  provides the information needed to describe such a hardware value.
> > +
> > +maintainers:
> > +  - Rob Clark <robdclark@...il.com>
> > +
> > +allOf:
> > +  - $ref: opp-v2-base.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    const: operating-points-v2-adreno
> > +
> > +patternProperties:
> > +  '^opp-?[0-9]+$':
> > +    type: object
> > +    additionalProperties: false
> > +
> > +    properties:
> > +      opp-hz: true
> > +
> > +      opp-level: true
> > +
> > +      opp-peak-kBps: true
> > +
> > +      opp-supported-hw: true
> > +
> > +      qcom,opp-acd-level:
> > +        description: |
> > +          A positive value representing the acd level associated with this
> 
> What is acd?

Adaptive Clock Distribution, a fancy name for clock throttling during voltage
droop. I will update the description to capture this.

> 
> > +          OPP node. This value is shared to GMU during GPU wake up. It may
> 
> What is GMU?

A co-processor which does power management for Adreno GPU.

> 
> > +          not be present for some OPPs and GMU will disable ACD while
> 
> acd or ACD?

should be uppercase everywhere in description.

> 
> > +          transitioning to that OPP.
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +    required:
> > +      - opp-hz
> > +      - opp-level
> > +
> > +required:
> > +  - compatible
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +
> 
> Drop blank line
> 
> > +    #include <dt-bindings/power/qcom-rpmpd.h>
> > +
> > +    gpu_opp_table: opp-table {
> > +        compatible = "operating-points-v2-adreno";
> > +
> > +        opp-550000000 {
> > +                opp-hz = /bits/ 64 <550000000>;
> > +                opp-level = <RPMH_REGULATOR_LEVEL_SVS>;
> > +                opp-peak-kBps = <6074219>;
> > +                qcom,opp-acd-level = <0xc0285ffd>;
> > +        };
> > +
> > +        opp-390000000 {
> > +                opp-hz = /bits/ 64 <390000000>;
> > +                opp-level = <RPMH_REGULATOR_LEVEL_LOW_SVS>;
> > +                opp-peak-kBps = <3000000>;
> > +                qcom,opp-acd-level = <0xc0285ffd>;
> 
> That's the same value used everywhere. What's the point? Just encode it
> in the driver.

I will update this to keep a different value. In a real implmentation,
these values may vary between OPPs. For eg:, please check the DT patch
in this series:

https://patchwork.freedesktop.org/patch/619413/

-Akhil

> 
> > +        };
> > +
> > +        opp-300000000 {
> > +                opp-hz = /bits/ 64 <300000000>;
> > +                opp-level = <RPMH_REGULATOR_LEVEL_LOW_SVS_D1>;
> > +                opp-peak-kBps = <2136719>;
> > +                /* Intentionally left out qcom,opp-acd-level property here */
> > +        };
> > +
> 
> Stray blank line
> 
> > +    };
> > 
> > -- 
> > 2.45.2
> >