Re: [PATCH v2 02/10] dt-bindings: devfreq: add mt8196-gpufreq binding

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 12/09/25 20:37, Nicolas Frattaroli ha scritto:
> On the MediaTek MT8196 SoC, the GPU has its power and frequency
> dynamically controlled by an embedded special-purpose MCU. This MCU is
> in charge of powering up the GPU silicon. It also provides us with a
> list of available OPPs at runtime, and is fully in control of all the
> regulator and clock fiddling it takes to reach a certain level of
> performance. It's also in charge of enforcing limits on power draw or
> temperature.
> 
> Add a binding for this device in the devfreq subdirectory, where it
> seems to fit in best considering its tasks.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> ---
>   .../bindings/devfreq/mediatek,mt8196-gpufreq.yaml  | 113 +++++++++++++++++++++
>   1 file changed, 113 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/devfreq/mediatek,mt8196-gpufreq.yaml b/Documentation/devicetree/bindings/devfreq/mediatek,mt8196-gpufreq.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..9d9efd4e70f1ef7ae446c833c15144beb9641b16
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/mediatek,mt8196-gpufreq.yaml
> @@ -0,0 +1,113 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/devfreq/mediatek,mt8196-gpufreq.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek MFlexGraphics Performance Controller
> +
> +maintainers:
> +  - Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> +
> +description: |
> +  A special-purpose embedded MCU to control power and frequency of GPU devices
> +  using MediaTek Flexible Graphics integration hardware.
> +
> +properties:
> +  $nodename:
> +    pattern: '^performance-controller@[a-f0-9]+$'
> +
> +  compatible:
> +    enum:
> +      - mediatek,mt8196-gpufreq
> +
> +  reg:
> +    items:
> +      - description: GPR memory area
> +      - description: RPC memory area
> +      - description: SoC variant ID register
> +
> +  reg-names:
> +    items:
> +      - const: gpr
> +      - const: rpc
> +      - const: hw_revision

hw-revision

> +
> +  clocks:
> +    items:
> +      - description: main clock of the embedded controller (EB)
> +      - description: core PLL
> +      - description: stack 0 PLL
> +      - description: stack 1 PLL
> +
> +  clock-names:
> +    items:
> +      - const: eb
> +      - const: mfgpll
> +      - const: mfgpll_sc0

What about using a bit more generic clock names?

main, gpu-core, gpu-stack0, gpu-stack1

...or something along that line :-)

> +      - const: mfgpll_sc1
> +
> +  mboxes:
> +    items:
> +      - description: FastDVFS events
> +      - description: frequency control
> +      - description: sleep control
> +      - description: timer control
> +      - description: frequency hopping control
> +      - description: hardware voter control
> +      - description: FastDVFS control
> +
> +  mbox-names:
> +    items:
> +      - const: fast-dvfs-event
> +      - const: gpufreq
> +      - const: sleep
> +      - const: timer
> +      - const: fhctl
> +      - const: ccf
> +      - const: fast-dvfs
> +
> +  shmem:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description: phandle to the shared memory region of the GPUEB MCU
> +
> +  "#performance-domain-cells":
> +    const: 0
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - clocks
> +  - clock-names
> +  - mboxes
> +  - mbox-names
> +  - shmem
> +  - "#performance-domain-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/mediatek,mt8196-clock.h>
> +
> +    gpufreq: performance-controller@4b09fd00 {

You're not using any phandle to gpufreq in this example, are you?

Drop that `gpufreq: ` :-)

> +        compatible = "mediatek,mt8196-gpufreq";
> +        reg = <0x4b09fd00 0x80>,
> +              <0x4b800000 0x1000>,
> +              <0x4b860128 0x4>;
> +        reg-names = "gpr", "rpc", "hw_revision";
> +        clocks = <&topckgen CLK_TOP_MFG_EB>,
> +                 <&mfgpll CLK_MFG_AO_MFGPLL>,
> +                 <&mfgpll_sc0 CLK_MFGSC0_AO_MFGPLL_SC0>,
> +                 <&mfgpll_sc1 CLK_MFGSC1_AO_MFGPLL_SC1>;
> +        clock-names = "eb", "mfgpll", "mfgpll_sc0",
> +                      "mfgpll_sc1";
> +        mboxes = <&gpueb_mbox 0>, <&gpueb_mbox 1>, <&gpueb_mbox 2>,
> +                 <&gpueb_mbox 3>, <&gpueb_mbox 4>, <&gpueb_mbox 5>,
> +                 <&gpueb_mbox 7>;
> +        mbox-names = "fast-dvfs-event", "gpufreq", "sleep", "timer", "fhctl",
> +                     "ccf", "fast-dvfs";
> +        shmem = <&gpufreq_shmem>;
> +        #performance-domain-cells = <0>;
> +    };
>