[email protected] writes:
> 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]>
Thanks, applying to davinci git.
Will queue for 2.6.38 (it's a bit too late for 2.6.37 as Linus only
wants real regression fixes after -rc6.)
Kevin
> ---
> 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,
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