linux-kernel - Re: [RFC 1/2] dt-bindings: thermal: sprd: Add virtual thermal documentation

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Date:   Fri, 27 Nov 2020 09:27:19 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     gao.yunxiao6@...il.com, rui.zhang@...el.com,
        daniel.lezcano@...aro.org, amitk@...nel.org, robh+dt@...nel.org,
        javi.merino@...nel.org
Cc:     linux-pm@...r.kernel.org, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        orsonzhai@...il.com, zhang.lyra@...il.com,
        "jeson.gao" <jeson.gao@...soc.com>
Subject: Re: [RFC 1/2] dt-bindings: thermal: sprd: Add virtual thermal
 documentation



On 11/27/20 8:35 AM, gao.yunxiao6@...il.com wrote:
> From: "jeson.gao" <jeson.gao@...soc.com>
> 
> virtual thermal node definition description in dts file
> 
> Signed-off-by: jeson.gao <jeson.gao@...soc.com>
> ---
>   .../thermal/sprd-virtual-thermal.yaml         | 38 +++++++++++++++++++
>   1 file changed, 38 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/thermal/sprd-virtual-thermal.yaml
> 
> diff --git a/Documentation/devicetree/bindings/thermal/sprd-virtual-thermal.yaml b/Documentation/devicetree/bindings/thermal/sprd-virtual-thermal.yaml
> new file mode 100644
> index 000000000000..3e3d2282e2a4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/sprd-virtual-thermal.yaml
> @@ -0,0 +1,38 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/thermal/sprd-virtual-thermal.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Spreadtrum virtual thermal driver bindings
> +
> +maintainers:
> +  - Yunxiao Gao <gao.yunxiao6@...il.com>
> +
> +properties:
> +  compatible:
> +    const: sprd,virtual-thermal
> +
> +  reg:
> +    description: specify the virtual sensor id.
> +    maxItems: 1
> +
> +  thmzone-names:
> +    description: specify per-core thermal zone name.
> +
> +required:
> +  - compatible
> +  - reg
> +  - thmzone-names
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    virtual_sensor: virtual-sensor@1 {
> +      compatible = "sprd,virtual-thermal";
> +      reg = <1>;
> +      thmzone-names = "ank0-thmzone","ank1-thmzone","ank2-thmzone",
> +                      "ank3-thmzone","ank4-thmzone","ank5-thmzone","prometheus6-tzone0",
> +                      "prometheus6-tzone1","prometheus7-thmzone";
> +    };
> 

It's coming back. There were attempts to solve this problem.
Javi tried to solved this using hierarchical thermal zones [1].
It was even agreed (IIRC during LPC) but couldn't continue. Then Eduardo
was going to continue this (last message at [3]). Unfortunately, 
development stopped.

I also have out-of-tree similar implementation for my Odroid-xu4,
which does no have an 'SoC' sensor, but have CPU sensors and needs
some aggregation function to get temperature.

I can pick up Javi's patches and continue 'hierarchical thermal zones'
approach.

Javi, Daniel, Rui what do you think?

Regards,
Lukasz

[1] https://lwn.net/Articles/666015/
[2] 
https://patchwork.kernel.org/project/linux-pm/patch/1448464186-26289-2-git-send-email-javi.merino@arm.com/
[3] 
https://patchwork.kernel.org/project/linux-pm/patch/1448464186-26289-3-git-send-email-javi.merino@arm.com/
[4] 
https://patchwork.kernel.org/project/linux-pm/patch/1448464186-26289-4-git-send-email-javi.merino@arm.com/
[5] 
https://patchwork.kernel.org/project/linux-pm/patch/1448464186-26289-5-git-send-email-javi.merino@arm.com/