Re: [PATCH v2 1/2] dt-bindings: devfreq: mediatek: Add mtk cci devfreq dt-bindings

Krzysztof Kozlowski
2022-04-08T08:17:34Z

On 08/04/2022 07:21, Johnson Wang wrote:
> Add devicetree binding of mtk cci devfreq on MediaTek SoC.
>

Thank you for your patch. There is something to discuss/improve.

> Signed-off-by: Johnson Wang <johnson.wang@mediatek.com>
> Signed-off-by: Jia-Wei Chang <jia-wei.chang@mediatek.com>
> ---
> .../devicetree/bindings/devfreq/mtk-cci.yaml | 72 +++++++++++++++++++
> 1 file changed, 72 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/devfreq/mtk-cci.yaml

Filename with vendor prefix, so something like:

mediatek,cci.yaml

Also please put it in the "interconnect" directory.

>
> diff --git a/Documentation/devicetree/bindings/devfreq/mtk-cci.yaml b/Documentation/devicetree/bindings/devfreq/mtk-cci.yaml
> new file mode 100644
> index 000000000000..ef4ea951025c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/mtk-cci.yaml
> @@ -0,0 +1,72 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/devfreq/mtk-cci.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek Cache Coherent Interconnect (CCI) frequency and voltage scaling
> +
> +maintainers:
> + - Jia-Wei Chang <jia-wei.chang@mediatek.com>
> +
> +description: |
> + MediaTek Cache Coherent Interconnect (CCI) uses the software devfreq module

Do not reference software implementation (devfreq).

> + to scale the clock frequency and adjust the voltage. MediaTek CCI shares
> + the same power supplies with CPU, so the scheduling involves with CPUfreq.

The same - cpufreq.

Instead, focus on the hardware, what do you describe here?

> +
> +properties:
> + compatible:
> + enum:
> + - mediatek,mt8183-cci
> + - mediatek,mt8186-cci
> +
> + clocks:
> + items:
> + - description:
> + The multiplexer for clock input of CPU cluster.
> + - description:
> + A parent of "cpu" clock which is used as an intermediate clock source
> + when the original CPU is under transition and not stable yet.
> +
> + clock-names:
> + items:
> + - const: cci
> + - const: intermediate
> +
> + operating-points-v2:
> + description:
> + For details, please refer to
> + Documentation/devicetree/bindings/opp/opp-v2.yaml

No need for description. Just "operating-points-v2: true".

"opp-table:true" could stay. My previous comment about its removal was a
wrong advice, because opp-table is used for a table being a children of
this device node.

Best regards,
Krzysztof