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 21:05:24 +0200
From:   <ansuelsmth@...il.com>
To:     "'Rob Herring'" <robh@...nel.org>
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



> -----Original Message-----
> From: Rob Herring <robh@...nel.org>
> Sent: Monday, September 28, 2020 8:09 PM
> 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.
> 

Should I still document it in the devfreq directory or somewhere else?

> > +
> > +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.
> 

Ok will change to v2.

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