linux-kernel - Re: [PATCH v5 0/5] ARM: EXYNOS: cpuidle: fix AFTR mode on boards with secure firmware enabled

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Date:	Tue, 05 Aug 2014 16:26:23 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>
Cc:	linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
	Sachin Kamat <sachin.kamat@...aro.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Tomasz Figa <t.figa@...sung.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linaro-kernel@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 0/5] ARM: EXYNOS: cpuidle: fix AFTR mode on boards with
 secure firmware enabled

On 05.08.2014 16:03, Daniel Lezcano wrote:
> On 08/05/2014 03:34 PM, Bartlomiej Zolnierkiewicz wrote:
>> Hi,
>>
>> This patch series adds support for AFTR idle mode on boards with
>> secure firmware enabled and allows EXYNOS cpuidle driver usage on
>> Exynos4x12 SoCs.
>>
>> It has been tested on Trats2 board (using Exynos4412 SoC with secure
>> firmware enabled) on which AFTR mode reduces power consumption by ~12%
>> when EXYNOS cpuidle driver is enabled (in both cases the default
>> exynos_defconfig config is used and CPU1-3 are offlined).
>
> As a sidenote:
>
> On my odroid-U2:
>   * 4 cpus online -> 130 mA
>   * 3 cpus online -> 164 mA
>   * 2 cpus online -> 160 mA
>   * 1 cpu online  -> 157 mA
>
> So were are consuming more when there are unplugged cpu ... any ideas ?

On which tree are you testing? Current next has ARMCLK down feature 
enabled. ARMCLK down may stop working after hotunplugging CPU:
http://www.spinics.net/lists/arm-kernel/msg352890.html

That was observed especially on Exynos4212 where ARMCLK down stops 
working permanently. On Trats2 (Exynos4412) the clock down stopped only 
a for short period after disabling CPU.

Best regards,
Krzysztof



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