On Wed, 20 Dec 2006 17:13:37 -0500
john stultz <[email protected]> wrote:
> +
> +unsigned int __init hpet_calibrate_tsc(void)
> +{
> + int tsc_start, hpet_start;
> + int tsc_now, hpet_now;
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + local_irq_disable();
> +
> + hpet_start = hpet_readl(HPET_COUNTER);
> + rdtscl(tsc_start);
> +
> + do {
> + local_irq_disable();
> + hpet_now = hpet_readl(HPET_COUNTER);
> + tsc_now = get_cycles_sync();
> + local_irq_restore(flags);
> + } while ((tsc_now - tsc_start) < TICK_COUNT &&
> + (hpet_now - hpet_start) < TICK_COUNT);
> +
> + return (tsc_now - tsc_start) * 1000000000L
> + / ((hpet_now - hpet_start) * hpet_period / 1000);
> +}
What a confused function. If called with local irqs disabled it'll fail to
enable interrupts in that loop. Perhaps that's deliberate, dunno.
Plus local_irq_save() disables interrupts, so the first local_irq_disable()
is not needed.
I will kill the unneeded local_irq_disable() and then shall back slowly away
from it.
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