linux-kernel - Re: [PATCH v6 07/52] dt-bindings: memory: tegra20: emc: Document OPP table and voltage regulator

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Date:   Tue, 27 Oct 2020 09:57:18 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>,
        Viresh Kumar <vireshk@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v6 07/52] dt-bindings: memory: tegra20: emc: Document OPP
 table and voltage regulator

On Mon, Oct 26, 2020 at 01:16:50AM +0300, Dmitry Osipenko wrote:
> The SoC core voltage can't be changed without taking into account the
> clock rate of External Memory Controller. Document OPP table that will
> be used for dynamic voltage frequency scaling, taking into account EMC
> voltage requirement. Document optional core voltage regulator, which is
> optional because some boards may have a fixed core regulator and still
> frequency scaling may be desired to have.

You need to document that property is optional in the binding.

Best regards,
Krzysztof

> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  .../memory-controllers/nvidia,tegra20-emc.txt      | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
> index 0a53adc6ccba..8d09b228ac42 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
> +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
> @@ -14,11 +14,23 @@ Properties:
>  - clocks : Should contain EMC clock.
>  - nvidia,memory-controller : Phandle of the Memory Controller node.
>  - #interconnect-cells : Should be 0.
> +- core-supply: Phandle of voltage regulator of the SoC "core" power domain.
> +- operating-points-v2: See ../bindings/opp/opp.txt for details.
>  
>  Child device nodes describe the memory settings for different configurations and clock rates.
>  
>  Example:
>  
> +	emc_icc_dvfs_opp_table: emc_opp_table0 {
> +		compatible = "operating-points-v2";
> +
> +		opp@...00000 {
> +			opp-microvolt = <950000 950000 1300000>;
> +			opp-hz = /bits/ 64 <36000000>;
> +		};
> +		...
> +	};
> +
>  	memory-controller@...0f400 {
>  		#address-cells = < 1 >;
>  		#size-cells = < 0 >;
> @@ -28,6 +40,8 @@ Example:
>  		interrupts = <0 78 0x04>;
>  		clocks = <&tegra_car TEGRA20_CLK_EMC>;
>  		nvidia,memory-controller = <&mc>;
> +		core-supply = <&core_vdd_reg>;
> +		operating-points-v2 = <&emc_icc_dvfs_opp_table>;
>  	}
>  
>  
> -- 
> 2.27.0
>