[PATCH v5 3/7] ARM: dts: Exynos542x/5800: add CPU OPP properties

Krzysztof Kozlowski k.kozlowski at samsung.com
Thu Dec 10 20:18:10 PST 2015

On 11.12.2015 13:13, Viresh Kumar wrote:
> On 11-12-15, 13:00, Krzysztof Kozlowski wrote:
>> It wasn't working like this. The cpu0 got the index from booting cpu, so
>> on 5420 cpu0 was A15 and on 5422 it was A7.
>> Maybe I am not aware of some changes recently in the kernel but how do
>> you want to assign the booting CPU proper number (not CPU0)?
> Okay, this is how it works and I don't think you need to change the
> order of CPUs based on machines.
> The boot CPU isn't controlled by the DT file but your bootloader, so
> it will be A15 on 5420 and A7 on 5422.
> Now if you keep the order in DT as: 0-3 A7 and 4-7 A15 irrespective of
> the SoCs, then this is how they will be assigned.
> Linux CPU numbers               Actual CPU assigned to them
>                                 5420            5422
> CPU0                            A15-0 (boot)    A7-0 (boot)
> CPU1                            A7-0            A7-1
> CPU2                            A7-1            A7-2
> CPU3                            A7-2            A7-3
> CPU4                            A7-3            A15-0
> CPU5                            A15-1           A15-1
> CPU6                            A15-2           A15-2
> CPU7                            A15-3           A15-3
> This happens because all non-boot CPUs will be added in the order they
> are present in DT.
> Now, there should be no *real* reason for you to want your CPUs to be
> always contiguous, isn't it?
> In the case of 5420, cpufreq will show related CPUs as:
> Policy0: CPU0,5-7, Policy1: CPU1-4
> and in the case of 5422, cpufreq will show related CPUs as:
> Policy0: CPU0-3, Policy1: CPU4-7
> And I think you should really fix this now..

We had such configuration before (before df09df6f9ac3). I don't see any
benefit in what you described. Where is the "thing" to be fixed? It is
mixed up. The contiguous ordering is easier to read and more natural.

Best regards,

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