linux-kernel - Re: [PATCHv2 8/8] devfreq: exynos4: Add busfreq driver for exynos4210/exynos4x12

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Date:	Thu, 13 Mar 2014 17:50:57 +0100
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
Cc:	myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
	rafael.j.wysocki@...el.com, nm@...com, b.zolnierkie@...saung.com,
	pawel.moll@....com, mark.rutland@....com, swarren@...dotorg.org,
	ijc+devicetree@...lion.org.uk, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCHv2 8/8] devfreq: exynos4: Add busfreq driver for
 exynos4210/exynos4x12


On Thursday, March 13, 2014 05:17:29 PM Chanwoo Choi wrote:
> This patch add busfreq driver for Exynos4210/Exynos4x12 memory interface

This patch adds DT binding documentation not the driver itself.

Same comment for the patch summary line.

> and bus to support DVFS(Dynamic Voltage Frequency Scaling) according to PPMU
> counters. PPMU (Performance Profiling Monitorings Units) of Exynos4 SoC provides
> PPMU counters for DMC(Dynamic Memory Controller) to check memory bus utilization
> and then busfreq driver adjusts dynamically the operating frequency/voltage
> by using DEVFREQ Subsystem.
> 
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> ---
>  .../devicetree/bindings/devfreq/exynos4_bus.txt    | 49 ++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/exynos4_bus.txt
> 
> diff --git a/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt
> new file mode 100644
> index 0000000..2a83fcc
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt
> @@ -0,0 +1,49 @@
> +
> +Exynos4210/4x12 busfreq driver
> +-----------------------------
> +
> +Exynos4210/4x12 Soc busfreq driver with devfreq for Memory bus frequency/voltage

SoC

> +scaling according to PPMU counters of memory controllers
> +
> +Required properties:
> +- compatible	: should contain Exynos4 SoC type as follwoing:

following

> +		  - "samsung,exynos4x12-busfreq" for Exynos4x12
> +		  - "samsung,exynos4210-busfreq" for Exynos4210
> +- reg		: offset and length of the ppmudmc0/1
> +		  - PPMU (Performance Profiling Monitoring Units)
> +		  : It is to profile performance event of DMC(Dynamic Memory
> +		  Controller) So, exynos4_bus.c can check memory bus utilization
> +		  by using PPMU of Exynos4 SoC.

It can be improved by changing ordering, i.e.

		  : PPMU of Exynos4 SoC is used to profile performance event of DMC (Dynamic
		  Memory Controller) so the driver can check memory bus utilization.

> +- clocks	: clock number of ppmudmc0/1
> +- clock-names	: clock name of ppmudmc0/1
> +- vdd_int-supply: regulator for interface block of Exynos4
> +
> +Optional properties:
> +- vdd_mif-supply: regulator for DMC block of Exynos4x12 if Exynos4x12 Soc

if using Exynos4x12 SoC

> +- regs-name	: register name of ppmudmc0/1
> +
> +All the required listed above must be defined under code busfreq with devfreq

required properties

> +Exmaple:

Example:

> +For Exynos4210 busfreq,

please add a newline here

> +	busfreq@...A0000 {
> +		compatible = "samsung,exynos4210-busfreq";
> +		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
> +		regs-name = "PPMU_DMC0", "PPMU_DMC1";
> +		clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
> +		clock-names = "ppmudmc0", "ppmudmc1";
> +
> +		vdd_int-supply = <&buck3_reg>;
> +	};
> +
> +For Exynos4x12 busfreq,

ditto

> +	busfreq@...A0000 {
> +		compatible = "samsung,exynos4x12-busfreq";
> +		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
> +		regs-name = "PPMU_DMC0", "PPMU_DMC1";
> +		clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
> +		clock-names = "ppmudmc0", "ppmudmc1";
> +
> +		vdd_mif-suppy = <&buck1_reg>;
> +		vdd_int-supply = <&buck3_reg>;
> +	};

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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