linux-kernel - Re: [PATCH v6 1/3] dt-bindings: soc: add mtk svs dt-bindings

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Date:   Wed, 8 Jan 2020 14:38:29 -0600
From:   Rob Herring <robh@...nel.org>
To:     Roger Lu <roger.lu@...iatek.com>
Cc:     Kevin Hilman <khilman@...nel.org>,
        Nicolas Boichat <drinkcat@...gle.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Fan Chen <fan.chen@...iatek.com>,
        HenryC Chen <HenryC.Chen@...iatek.com>,
        YT Lee <yt.lee@...iatek.com>,
        Xiaoqing Liu <Xiaoqing.Liu@...iatek.com>,
        Charles Yang <Charles.Yang@...iatek.com>,
        Angus Lin <Angus.Lin@...iatek.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Nishanth Menon <nm@...com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v6 1/3] dt-bindings: soc: add mtk svs dt-bindings

On Tue, Jan 07, 2020 at 03:01:52PM +0800, Roger Lu wrote:
> Document the binding for enabling mtk svs on MediaTek SoC.
> 
> Signed-off-by: Roger Lu <roger.lu@...iatek.com>
> ---
>  .../devicetree/bindings/power/mtk-svs.txt     | 76 +++++++++++++++++++
>  1 file changed, 76 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/mtk-svs.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/mtk-svs.txt b/Documentation/devicetree/bindings/power/mtk-svs.txt
> new file mode 100644
> index 000000000000..9a3e81b9e1d2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/mtk-svs.txt
> @@ -0,0 +1,76 @@
> +* Mediatek Smart Voltage Scaling (MTK SVS)
> +
> +This describes the device tree binding for the MTK SVS controller (bank)
> +which helps provide the optimized CPU/GPU/CCI voltages. This device also
> +needs thermal data to calculate thermal slope for accurately compensate
> +the voltages when temperature change.
> +
> +Required properties:
> +- compatible:
> +  - "mediatek,mt8183-svs" : For MT8183 family of SoCs
> +- reg: Address range of the MTK SVS controller.
> +- interrupts: IRQ for the MTK SVS controller.
> +- clocks, clock-names: Clocks needed for the svs hardware. required
> +                       clocks are:
> +		       "main": Main clock for svs controller to work.
> +- nvmem-cells: Phandle to the calibration data provided by a nvmem device.
> +- nvmem-cell-names: Should be "svs-calibration-data" and "calibration-data"
> +
> +Subnodes:
> +- svs-cpu-little: SVS bank device node of little CPU
> +  compatible: "mediatek,mt8183-svs-cpu-little"
> +  operating-points-v2: OPP table hooked by SVS little CPU bank.
> +		       SVS will optimze this OPP table voltage part.
> +  vcpu-little-supply: PMIC buck of little CPU
> +- svs-cpu-big: SVS bank device node of big CPU
> +  compatible: "mediatek,mt8183-svs-cpu-big"
> +  operating-points-v2: OPP table hooked by SVS big CPU bank.
> +		       SVS will optimze this OPP table voltage part.
> +  vcpu-big-supply: PMIC buck of big CPU
> +- svs-cci: SVS bank device node of CCI
> +  compatible: "mediatek,mt8183-svs-cci"
> +  operating-points-v2: OPP table hooked by SVS CCI bank.
> +		       SVS will optimze this OPP table voltage part.
> +  vcci-supply: PMIC buck of CCI
> +- svs-gpu: SVS bank device node of GPU
> +  compatible: "mediatek,mt8183-svs-gpu"
> +  operating-points-v2: OPP table hooked by SVS GPU bank.
> +		       SVS will optimze this OPP table voltage part.
> +  vgpu-supply: PMIC buck of GPU
> +
> +Example:
> +
> +	svs: svs@...0b000 {
> +		compatible = "mediatek,mt8183-svs";
> +		reg = <0 0x1100b000 0 0x1000>;
> +		interrupts = <GIC_SPI 127 IRQ_TYPE_LEVEL_LOW>;
> +		clocks = <&infracfg CLK_INFRA_THERM>;
> +		clock-names = "main_clk";
> +		nvmem-cells = <&svs_calibration>, <&thermal_calibration>;
> +		nvmem-cell-names = "svs-calibration-data", "calibration-data";
> +
> +		svs_cpu_little: svs-cpu-little {
> +			compatible = "mediatek,mt8183-svs-cpu-little";
> +			operating-points-v2 = <&cluster0_opp>;
> +			vcpu-little-supply = <&mt6358_vproc12_reg>;
> +		};

I don't think this is a good binding. This information already exists 
elsewhere in the DT, so your driver should just look in those nodes. 
For example the regulator can be in the cpu nodes or the OPP table 
itself.

Rob