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    SubjectRe: [PATCH v1] PM / Domains: Add tracepoints
    On Tue, Oct 01, 2019 at 01:03:43PM -0400, Steven Rostedt wrote:
    > On Tue, 1 Oct 2019 09:35:42 -0700
    > Matthias Kaehlcke <mka@chromium.org> wrote:
    >
    > > How about this instead:
    > >
    > > Add tracepoints for genpd_power_on, genpd_power_off and
    > > genpd_set_performance_state. The tracepoints can help with
    > > understanding power domain behavior of a given device, which
    > > may be particularly interesting for battery powered devices
    > > and suspend/resume.
    >
    > Do you have a use case example to present?

    TBH I'm not looking into a specific use case right now. While
    peeking around in /sys/kernel/debug/tracing/events to learn more
    about existing tracepoints that might be relevant for my work
    I noticed the absence of genpd ones and it seemed a good idea to
    add them preemptively. Conceptually they seem similar to the
    existing regulator_enable/disable and cpu_idle tracepoints.

    As an abstract use case I could see power analysis on battery
    powered devices during suspend. genpd_power_on/off allow to see
    which power domains remain on during suspend, and might give
    insights for possible power saving options. Examples could be that
    a power domain stays unexpectedly on due to a misconfiguration, or
    two power domains remain on when it could be only one if you just
    moved that one pin/port over to the other domain in the next
    hardware revision.

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