linux-kernel - Re: [PATCH v7 07/13] dt-bindings: memory-controllers: add Exynos5422 DMC device description

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Date:   Tue, 7 May 2019 12:04:22 -0500
From:   Rob Herring <robh@...nel.org>
To:     Lukasz Luba <l.luba@...tner.samsung.com>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        b.zolnierkie@...sung.com, krzk@...nel.org, kgene@...nel.org,
        cw00.choi@...sung.com, kyungmin.park@...sung.com,
        m.szyprowski@...sung.com, s.nawrocki@...sung.com,
        myungjoo.ham@...sung.com, keescook@...omium.org, tony@...mide.com,
        jroedel@...e.de, treding@...dia.com, digetx@...il.com,
        willy.mh.wolff.ml@...il.com
Subject: Re: [PATCH v7 07/13] dt-bindings: memory-controllers: add Exynos5422
 DMC device description

On Mon, May 06, 2019 at 05:11:55PM +0200, Lukasz Luba wrote:
> The patch adds description for DT binding for a new Exynos5422 Dynamic
> Memory Controller device.
> 
> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
> ---
>  .../bindings/memory-controllers/exynos5422-dmc.txt | 74 ++++++++++++++++++++++
>  1 file changed, 74 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt b/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
> new file mode 100644
> index 0000000..be602a9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
> @@ -0,0 +1,74 @@
> +* Exynos5422 frequency and voltage scaling for Dynamic Memory Controller device
> +
> +The Samsung Exynos5422 SoC has DMC (Dynamic Memory Controller) to which the DRAM
> +memory chips are connected. The driver is to monitor the controller in runtime
> +and switch frequency and voltage. To monitor the usage of the controller in
> +runtime, the driver uses the PPMU (Platform Performance Monitoring Unit), which
> +is able to measure the current load of the memory.
> +When 'userspace' governor is used for the driver, an application is able to
> +switch the DMC and memory frequency.
> +
> +Required properties for DMC device for Exynos5422:
> +- compatible: Should be "samsung,exynos5422-dmc".
> +- clock-names : the name of clock used by the controller.
> +- clocks : phandles for clock specified in "clock-names" property.

Need to enumerate the clocks and their order.

> +- devfreq-events : phandles for PPMU devices connected to this DMC.
> +- vdd-supply : phandle for voltage regulator which is connected.
> +- reg : registers of two CDREX controllers.
> +- operating-points-v2 : phandle for OPPs described in v2 definition.
> +- device-handle : phandle of the connected DRAM memory device. For more
> +	information please refer to Documentation

Documentation... ?

> +- devfreq-events : phandles of the PPMU events used by the controller.
> +- samsung,syscon-chipid : phandle of the ChipID used by the controller.
> +- samsung,syscon-clk : phandle of the clock register set used by the controller.

Looks like a hack. Can't you get this from the clocks property? What is 
this for?

> +
> +Example:
> +
> +	ppmu_dmc0_0: ppmu@...00000 {
> +		compatible = "samsung,exynos-ppmu";
> +		reg = <0x10d00000 0x2000>;
> +		clocks = <&clock CLK_PCLK_PPMU_DREX0_0>;
> +		clock-names = "ppmu";
> +		events {
> +			ppmu_event_dmc0_0: ppmu-event3-dmc0_0 {
> +				event-name = "ppmu-event3-dmc0_0";
> +			};
> +		};
> +	};
> +
> +	dmc: memory-controller@...20000 {
> +		compatible = "samsung,exynos5422-dmc";
> +		reg = <0x10c20000 0x100>, <0x10c30000 0x100>,
> +		clocks = 	<&clock CLK_FOUT_SPLL>,
> +				<&clock CLK_MOUT_SCLK_SPLL>,
> +				<&clock CLK_FF_DOUT_SPLL2>,
> +				<&clock CLK_FOUT_BPLL>,
> +				<&clock CLK_MOUT_BPLL>,
> +				<&clock CLK_SCLK_BPLL>,
> +				<&clock CLK_MOUT_MX_MSPLL_CCORE>,
> +				<&clock CLK_MOUT_MX_MSPLL_CCORE_PHY>,
> +				<&clock CLK_MOUT_MCLK_CDREX>,
> +				<&clock CLK_DOUT_CLK2X_PHY0>,
> +				<&clock CLK_CLKM_PHY0>,
> +				<&clock CLK_CLKM_PHY1>;
> +		clock-names =	"fout_spll",
> +				"mout_sclk_spll",
> +				"ff_dout_spll2",
> +				"fout_bpll",
> +				"mout_bpll",
> +				"sclk_bpll",
> +				"mout_mx_mspll_ccore",
> +				"mout_mx_mspll_ccore_phy",
> +				"mout_mclk_cdrex",
> +				"dout_clk2x_phy0",
> +				"clkm_phy0",
> +			        "clkm_phy1";
> +		operating-points-v2 = <&dmc_opp_table>;
> +		devfreq-events = <&ppmu_event3_dmc0_0>,	<&ppmu_event3_dmc0_1>,
> +				<&ppmu_event3_dmc1_0>, <&ppmu_event3_dmc1_1>;
> +		operating-points-v2 = <&dmc_opp_table>;
> +		device-handle = <&samsung_K3QF2F20DB>;
> +		vdd-supply = <&buck1_reg>;
> +		samsung,syscon-clk = <&clock>;
> +		samsung,syscon-chipid = <&chipid>;
> +	};
> -- 
> 2.7.4
>