linux-hardening - Re: [PATCH v8 1/5] dt-bindings: gpu: mali-valhall-csf: add mediatek,mt8196-mali variant

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Message-ID: <6599426.lOV4Wx5bFT@workhorse>
Date: Tue, 28 Oct 2025 21:51:43 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Liviu Dudau <liviu.dudau@....com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Jassi Brar <jassisinghbrar@...il.com>, Chia-I Wu <olvaffe@...il.com>,
 Chen-Yu Tsai <wenst@...omium.org>, Steven Price <steven.price@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Matthias Brugger <matthias.bgg@...il.com>, Kees Cook <kees@...nel.org>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Ulf Hansson <ulf.hansson@...aro.org>, kernel@...labora.com,
 dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org, linux-hardening@...r.kernel.org,
 linux-pm@...r.kernel.org
Subject:
 Re: [PATCH v8 1/5] dt-bindings: gpu: mali-valhall-csf: add
 mediatek,mt8196-mali variant

On Tuesday, 28 October 2025 18:12:35 Central European Standard Time Liviu Dudau wrote:
> On Fri, Oct 17, 2025 at 05:31:08PM +0200, Nicolas Frattaroli wrote:
> > The Mali-based GPU on the MediaTek MT8196 SoC uses a separate MCU to
> > control the power and frequency of the GPU. This is modelled as a power
> > domain and clock provider.
> > 
> > It lets us omit the OPP tables from the device tree, as those can now be
> > enumerated at runtime from the MCU.
> > 
> > Add the necessary schema logic to handle what this SoC expects in terms
> > of clocks and power-domains.
> > 
> > Reviewed-by: Rob Herring (Arm) <robh@...nel.org>
> > Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> > Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
> > ---
> >  .../bindings/gpu/arm,mali-valhall-csf.yaml         | 37 +++++++++++++++++++++-
> >  1 file changed, 36 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml b/Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml
> > index 613040fdb444..860691ce985e 100644
> > --- a/Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml
> > +++ b/Documentation/devicetree/bindings/gpu/arm,mali-valhall-csf.yaml
> > @@ -45,7 +45,9 @@ properties:
> >      minItems: 1
> >      items:
> >        - const: core
> > -      - const: coregroup
> > +      - enum:
> > +          - coregroup
> > +          - stacks
> >        - const: stacks
> 
> I'm not sure how to parse this part of the change. We're overwriting the property
> for mt8196-mali anyway so why do we need this? And if we do, should 'stacks'
> still remain as a const?

The properties section outside of the if branches outside here
specifies a pattern of properties that matches for all devices.

In this case, I changed it so that the second clock-names item
may either be "coregroup" or "stacks". Yes, the third "stacks"
remains, though if you wanted to be extra precise you could
then specify in the non-MT8196 cases that we should not have
stacks followed by stacks, but I'd wager some checker for
duplicate names may already catch that.

However, I don't think it's a big enough deal to reroll this
series again.

Kind regards,
Nicolas Frattaroli

> 
> Best regards,
> Liviu
> 
> >  
> >    mali-supply: true
> > @@ -110,6 +112,27 @@ allOf:
> >          power-domain-names: false
> >        required:
> >          - mali-supply
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: mediatek,mt8196-mali
> > +    then:
> > +      properties:
> > +        mali-supply: false
> > +        sram-supply: false
> > +        operating-points-v2: false
> > +        power-domains:
> > +          maxItems: 1
> > +        power-domain-names: false
> > +        clocks:
> > +          maxItems: 2
> > +        clock-names:
> > +          items:
> > +            - const: core
> > +            - const: stacks
> > +      required:
> > +        - power-domains
> >  
> >  examples:
> >    - |
> > @@ -145,5 +168,17 @@ examples:
> >              };
> >          };
> >      };
> > +  - |
> > +    gpu@...00000 {
> > +        compatible = "mediatek,mt8196-mali", "arm,mali-valhall-csf";
> > +        reg = <0x48000000 0x480000>;
> > +        clocks = <&gpufreq 0>, <&gpufreq 1>;
> > +        clock-names = "core", "stacks";
> > +        interrupts = <GIC_SPI 606 IRQ_TYPE_LEVEL_HIGH 0>,
> > +                     <GIC_SPI 605 IRQ_TYPE_LEVEL_HIGH 0>,
> > +                     <GIC_SPI 604 IRQ_TYPE_LEVEL_HIGH 0>;
> > +        interrupt-names = "job", "mmu", "gpu";
> > +        power-domains = <&gpufreq>;
> > +    };
> >  
> >  ...
> > 
> 
>