linux-kernel - Re: [PATCH 1/2] time: Introduce one suspend clocksource to compensate the suspend time

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Date:   Tue, 17 Jul 2018 13:11:33 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Mark Brown <broonie@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] time: Introduce one suspend clocksource to compensate
 the suspend time

On Tue, Jul 17, 2018 at 12:55 AM, Baolin Wang <baolin.wang@...aro.org> wrote:
> On some hardware with multiple clocksources, we have coarse grained
> clocksources that support the CLOCK_SOURCE_SUSPEND_NONSTOP flag, but
> which are less than ideal for timekeeping whereas other clocksources
> can be better candidates but halt on suspend.
>
> Currently, the timekeeping core only supports timing suspend using
> CLOCK_SOURCE_SUSPEND_NONSTOP clocksources if that clocksource is the
> current clocksource for timekeeping.
>
> As a result, some architectures try to implement read_persistent_clock64()
> using those non-stop clocksources, but isn't really ideal, which will
> introduce more duplicate code. To fix this, provide logic to allow a
> registered SUSPEND_NONSTOP clocksource, which isn't the current
> clocksource, to be used to calculate the suspend time.
>
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
> Changes from RFC v1:
>  - Improve commit message.
>  - Remove the WARN_ON_ONCE().
>  - Fix some coding style issues.
>  - Do not force to select a replacement suspend clocksource.

Thanks again, I'll get this queued up for testing.

thanks
-john