linux-kernel - Re: [PATCH 2/2] dt-bindings: devfreq: Document L2 Krait CPU Cache devfreq driver

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Date:   Mon, 28 Sep 2020 13:08:39 -0500
From:   Rob Herring <robh@...nel.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: devfreq: Document L2 Krait CPU Cache
 devfreq driver

On Sun, Sep 27, 2020 at 06:05:13PM +0200, Ansuel Smith wrote:
> Document dedicated L2 Krait CPU Cache devfreq scaling driver.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---
>  .../bindings/devfreq/krait-cache-devfreq.yaml | 77 +++++++++++++++++++
>  1 file changed, 77 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/krait-cache-devfreq.yaml
> 
> diff --git a/Documentation/devicetree/bindings/devfreq/krait-cache-devfreq.yaml b/Documentation/devicetree/bindings/devfreq/krait-cache-devfreq.yaml
> new file mode 100644
> index 000000000000..099ed978e022
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/krait-cache-devfreq.yaml
> @@ -0,0 +1,77 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/cpufreq/krait-cache-devfreq.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: DEVFREQ driver for Krait L2 Cpu Cache Frequency Scaling

Bindings are for h/w devices, not collections of properties for some 
driver. Define a binding for L2 cache and add on to it what you need.

> +
> +maintainers:
> +  - Ansuel Smith <ansuelsmth@...il.com>
> +
> +description: |
> +  This Scale the Krait CPU L2 Cache Frequency and optionally voltage
> +  when the Cpu Frequency is changed (using the cpufreq notifier).
> +
> +  Cache is scaled with the max frequency across all core and the cache
> +  frequency will scale based on the configured threshold in the dts.
> +
> +  The cache thresholds can be set to 3+ frequency bin, idle, nominal and
> +  high.
> +
> +properties:
> +  compatible:
> +    const: qcom,krait-cache
> +
> +  clocks:
> +    $ref: "/schemas/types.yaml#/definitions/phandle"

'clocks' already has a type defined. You just need how many and what 
each entry is.

> +    description: Phandle to the L2 CPU clock
> +
> +  clock-names:
> +    const: "l2"
> +
> +  voltage-tolerance:
> +    description: Same voltage tolerance of the Krait CPU

Needs a vendor prefix and unit suffix.

> +
> +  l2-cpufreq:
> +    description: |
> +      Threshold used by the driver to scale the L2 cache.
> +      If the max CPU Frequency is more than the set frequency,
> +      the driver will transition to the next frequency bin.
> +      Value is in kHz
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 3
> +    items:
> +      - description: idle
> +      - description: nominal
> +      - description: high
> +
> +  l2-supply:
> +    $ref: "/schemas/types.yaml#/definitions/phandle"
> +    description: Phandle to the L2 regulator supply.
> +
> +  opp-table: true
> +
> +required:
> +  - compatible
> +  - clocks
> +  - clock-names
> +  - voltage-tolerance
> +  - l2-cpufreq
> +
> +examples:
> +  - |
> +    qcom-krait-cache {
> +      compatible = "qcom,krait-cache";
> +      clocks = <&kraitcc 4>;
> +      clock-names = "l2";
> +      l2-cpufreq = <384000 600000 1200000>;
> +      l2-supply = <&smb208_s1a>;
> +
> +      operating-points = <

Not documented and generally deprecated.

> +        /* kHz    uV */
> +        384000  1100000
> +        1000000  1100000
> +        1200000  1150000
> +      >;
> +    };
> -- 
> 2.27.0
>