On Wednesday 25 September 2013 03:32 AM, Uwe Kleine-König wrote:
> clockevents_config_and_register is superior compared to setting
> shift/mult and {min,max}_delta_ns by hand.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de>
> ---
> Hello,
>
> I wonder where the 50 us limit comes from. This is not a hardware limit,
> is it?
>
> Best regards
> Uwe
>
> arch/arm/mach-davinci/time.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/mach-davinci/time.c b/arch/arm/mach-davinci/time.c
> index 7a55b5c..627bf8b 100644
> --- a/arch/arm/mach-davinci/time.c
> +++ b/arch/arm/mach-davinci/time.c
> @@ -331,7 +331,6 @@ static void davinci_set_mode(enum clock_event_mode mode,
>
> static struct clock_event_device clockevent_davinci = {
> .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> - .shift = 32,
> .set_next_event = davinci_set_next_event,
> .set_mode = davinci_set_mode,
> };
> @@ -397,14 +396,11 @@ void __init davinci_timer_init(void)
>
> /* setup clockevent */
> clockevent_davinci.name = id_to_name[timers[TID_CLOCKEVENT].id];
> - clockevent_davinci.mult = div_sc(davinci_clock_tick_rate, NSEC_PER_SEC,
> - clockevent_davinci.shift);
> - clockevent_davinci.max_delta_ns =
> - clockevent_delta2ns(0xfffffffe, &clockevent_davinci);
> - clockevent_davinci.min_delta_ns = 50000; /* 50 usec */
>
> clockevent_davinci.cpumask = cpumask_of(0);
> - clockevents_register_device(&clockevent_davinci);
> + /* min tick corresponds to 50 usec assuming a 24 MHz clock */
> + clockevents_config_and_register(&clockevent_davinci,
> + davinci_clock_tick_rate, 1200, 0xfffffffe);
Min ticks can be set to 1, IMO. I think the 50usec limit used earlier
should have actually been 50ns assuming a 24MHz clock.
Prabhakar,
Can you please test this patch on a DaVinci platform you have with 1200
replaced with 1. I currently do not have access to a board.
Thanks,
Sekhar
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