Re: [PATCH v5 0/5] ARM: EXYNOS: cpuidle: fix AFTR mode on boards with secure firmware enabled
From: Krzysztof Kozlowski
Date: Fri Sep 05 2014 - 08:28:18 EST
On wto, 2014-08-05 at 17:07 +0200, Daniel Lezcano wrote:
> On 08/05/2014 04:26 PM, Krzysztof Kozlowski wrote:
> > 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.
> Hi Krzysztof,
> I tested the patches you mentioned above on top of this patchset.
> You are right this is directly related to the ARMCLK but the behavior
> may be not as you expect I think.
> When I boot:
> 4 cpus online => 131 mA
> Then I unplug one by one the cpus:
> 3 cpus online => 127 mA
> 2 cpus online => 123 mA
> 1 cpu online => 120 mA
> This is consistent.
> But now, I online the cpus:
> 2 cpus online => 162 mA
> 3 cpus online => 165 mA
> 4 cpus online => 131 mA
> -- side note --
> Please note, I did not disable the cpuidle neither the AFTR state and
> the kernel did not hang but I don't see the noticeable power saving we
> should be observing when there is one cpu remaining entering the AFTR
> state (cpuidle stats show we enter AFTR). So there is definitively
> something wrong with this state.
Strange things happen... on current next-20140904 I couldn't reproduce
this inconsistent energy consumption after hotplug. At least on Trats2
(Exynos4412) and Gear1 (Exynos4212) it behaves consistently (and
properly with my patches).
Anyway I'll respin the patchset.
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