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

AngeloGioacchino Del Regno
2025-09-15T10:28:40Z

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>;
> + };
>