• John Stultz's avatar
    time: Add timekeeping_inject_sleeptime · 304529b1
    John Stultz authored
    Some platforms cannot implement read_persistent_clock, as
    their RTC devices are only accessible when interrupts are enabled.
    This keeps them from being used by the timekeeping code on resume
    to measure the time in suspend.
    
    The RTC layer tries to work around this, by calling do_settimeofday
    on resume after irqs are reenabled to set the time properly. However,
    this only corrects CLOCK_REALTIME, and does not properly adjust
    the sleep time value. This causes btime in /proc/stat to be incorrect
    as well as making the new CLOCK_BOTTTIME inaccurate.
    
    This patch resolves the issue by introducing a new timekeeping hook
    to allow the RTC layer to inject the sleep time on resume.
    
    The code also checks to make sure that read_persistent_clock is
    nonfunctional before setting the sleep time, so that should the RTC's
    HCTOSYS option be configured in on a system that does support
    read_persistent_clock we will not increase the total_sleep_time twice.
    
    CC: Arve Hjønnevåg <arve@android.com>
    CC: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    304529b1
timekeeping.c 28.4 KB