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    SubjectRe: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support
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    On 08/07/17 13:09, Rafael J. Wysocki wrote:
    > On Friday, July 07, 2017 06:06:30 PM Dietmar Eggemann wrote:
    >> On 07/07/17 17:18, Rafael J. Wysocki wrote:
    >>> On Fri, Jul 7, 2017 at 6:01 PM, Dietmar Eggemann
    >>> <dietmar.eggemann@arm.com> wrote:
    >>>> On 06/07/17 11:40, Viresh Kumar wrote:
    >>>>> On 06-07-17, 10:49, Dietmar Eggemann wrote:
    >>
    >> [...]
    >>
    >>>> So what about I call arch_set_freq_scale() in __cpufreq_notify_transition() in the
    >>>> CPUFREQ_POSTCHANGE case for slow-switching and in cpufreq_driver_fast_switch() for
    >>>> fast-switching?
    >>>
    >>> Why don't you do this in drivers instead of in the core?
    >>>
    >>> Ultimately, the driver knows what frequency it has requested, so why
    >>> can't it call arch_set_freq_scale()?
    >>
    >> That's correct but for arm/arm64 we have a lot of different cpufreq
    >> drivers to deal with. And doing this call to arch_set_freq_scale() once
    >> in the cpufreq core will cover them all.
    >>
    >> [...]
    >
    > I'm sort of wondering how many is "a lot" really. For instance, do you really
    > want all of the existing ARM platforms to use the new stuff even though
    > it may regress things there in principle?

    Yeah, in mainline we probably only care about a couple of them, I know
    about cpufreq-dt.c, mt8173-cpufreq.c and arm_big_little.c.
    But a lot of development in arm64 still happens outside mainline and we
    would have to inform people to provision their cpufreq drivers with this
    functionality.

    With a solution in cpufreq.c we could just implement the functionality
    in the arch which we then connect to the call in cpufreq.c.

    > Anyway, if everyone agrees that doing it in the core is the way to go (Peter?),
    > why don't you introduce a __weak function for setting policy->cur and
    > override it from your arch so as to call arch_set_freq_scale() from there?

    Yes, I will change this. The #define approach is not really necessary
    here since we're not in the scheduler hot-path and inlining is not
    really required here.

    Thanks,

    -- Dietmar

    [...]

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