From: Andreas Gaeer <[email protected]> Overwrite the default implementation of sched_clock that is based on jiffies by something more precise. This improves timestamps in ftrace. Implementation is copied from OMAP platform code.
Signed-off-by: Andreas Gaeer <[email protected]> --- arch/arm/mach-davinci/time.c | 24 +++++++++++++++++++++++- 1 files changed, 23 insertions(+), 1 deletions(-) diff --git a/arch/arm/mach-davinci/time.c b/arch/arm/mach-davinci/time.c index 0f21c36..5d1eea0 100644 --- a/arch/arm/mach-davinci/time.c +++ b/arch/arm/mach-davinci/time.c @@ -272,15 +272,36 @@ static cycle_t read_cycles(struct clocksource *cs) return (cycles_t)timer32_read(t); } +/* + * Kernel assumes that sched_clock can be called early but may not have + * things ready yet. + */ +static cycle_t read_dummy(struct clocksource *cs) +{ + return 0; +} + + static struct clocksource clocksource_davinci = { .rating = 300, - .read = read_cycles, + .read = read_dummy, .mask = CLOCKSOURCE_MASK(32), .shift = 24, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; /* + * Overwrite weak default sched_clock with something more precise + */ +unsigned long long notrace sched_clock(void) +{ + const cycle_t cyc = clocksource_davinci.read(&clocksource_davinci); + + return clocksource_cyc2ns(cyc, clocksource_davinci.mult, + clocksource_davinci.shift); +} + +/* * clockevent */ static int davinci_set_next_event(unsigned long cycles, @@ -377,6 +398,7 @@ static void __init davinci_timer_init(void) davinci_clock_tick_rate = clk_get_rate(timer_clk); /* setup clocksource */ + clocksource_davinci.read = read_cycles; clocksource_davinci.name = id_to_name[clocksource_id]; clocksource_davinci.mult = clocksource_khz2mult(davinci_clock_tick_rate/1000, -- 1.7.2.2 _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
