linux-kernel - Re: [PATCH v2 1/2] clk: samsung: exynos4: Enable ARMCLK down feature

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Message-ID: <CAD8Lp45UtZ_aao2ScUUjRq9AfnxGq9GuT24SLzY-koeBfTTDCw@mail.gmail.com>
Date:	Mon, 21 Jul 2014 13:51:59 +0100
From:	Daniel Drake <drake@...lessm.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Tomasz Figa <t.figa@...sung.com>,
	Mike Turquette <mturquette@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v2 1/2] clk: samsung: exynos4: Enable ARMCLK down feature

On Fri, Jul 18, 2014 at 3:36 PM, Krzysztof Kozlowski
<k.kozlowski@...sung.com> wrote:
> Enable ARMCLK down feature on all Exynos4 SoCs. The frequency of
> ARMCLK will be reduced upon entering idle mode (WFI or WFE).
>
> The feature behaves like very fast cpufreq ondemand governor. In idle
> mode this reduces energy consumption on full frequency chosen by
> cpufreq governor by approximately:
>  - Trats2:  6.5% (153 mA -> 143 mA)
>  - Trats:  33.0% (180 mA -> 120 mA)
>  - Gear1:  27.0% (180 mA -> 130 mA)
>
> The patch uses simillar settings as Exynos5250 (clk-exynos5250.c),
> except it disables clock up feature and on Exynos4412 ARMCLK down is
> enabled for all 4 cores.
>
> Tested on Trats board (Exynos4210), Trats2 board (Exynos4412) and
> Samsung Gear 1 (Exynos4212).
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

Tested on ODROID-U2, seems to be working. I don't have a way of
measuring the power usage, but the system seems as stable as before.

Tested-by: Daniel Drake <drake@...lessm.com>
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