Re: [PATCH 2/4] arm: dts: exynos: add exynos5420 cpu capacity-dmips-mhz information

[Dietmar Eggemann]

On 03/09/17 20:56, Krzysztof Kozlowski wrote:
> On Thu, Aug 31, 2017 at 11:36:07AM +0100, Dietmar Eggemann wrote:
>> On 30/08/17 21:26, Krzysztof Kozlowski wrote:
>>> On Wed, Aug 30, 2017 at 03:41:18PM +0100, Dietmar Eggemann wrote:

[...]

>>>> The patch has been tested on Samsung Chromebook 2 13" (peach-pi, Exynos
>>>> 5800).
>>>>
>>>> $ cat /sys/devices/system/cpu/cpu*/cpu_capacity
>>>> 1024
>>>> 1024
>>>> 1024
>>>> 1024
>>>> 389
>>>> 389
>>>> 389
>>>> 389
>>>
>>> I am missing something... shouldn't this be 539? Or is it scaled with
>>> the clock-frequency (1 GHz) value?
>>
>> Yeah, the capacity-dmips-mhz dt value of 539 for the little cpus is
>> scaled by 1.3/1.8 (max cpu capacity/ system wide max cpu capacity):
>>
>> 539 * 1.3/1.8 = 389
>>
>> This max cpu capacity scaling is part of both solutions, the 'cpu
>> capacity-dmips-mhz' and the 'cpu_efficiency/clock-frequency dt property'
>> one.
>>
>> The (original*) cpu capacity on a heterogeneous platform expresses uArch
>> and max cpu frequency differences between the (logical) cpus of the
>> system.
>>
>> * not further reduced by rt and/or irq pressure.
>>
>> [...]
> 
> Thanks for explanation, looks fine for me. I'll take it after merge
> window.

Nice, since the 'cpu capacity-dmips-mhz' is already supported for arm
(and used by TC2 (vexpress-v2p-ca15_a7.dts)) this can be done
independently of the actual removal of the
'cpu_efficiency/clock-frequency dt property' solution in patch 1/4.

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