• Baolin Wang's avatar
    time: Introduce one suspend clocksource to compensate the suspend time · 39232ed5
    Baolin Wang authored
    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.
    
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Miroslav Lichvar <mlichvar@redhat.com>
    Cc: Richard Cochran <richardcochran@gmail.com>
    Cc: Prarit Bhargava <prarit@redhat.com>
    Cc: Stephen Boyd <sboyd@kernel.org>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
    Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarBaolin Wang <baolin.wang@linaro.org>
    [jstultz: minor tweaks to merge with previous resume changes]
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    39232ed5
clocksource.c 33.1 KB