Messages in this thread | | | Date | Fri, 14 Jun 2019 20:17:14 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes |
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On Thu, 23 May 2019, Ricardo Neri wrote: > +/** > + * hpet_set_comparator() - Helper function for setting comparator register > + * @num: The timer ID > + * @cmp: The value to be written to the comparator/accumulator > + * @period: The value to be written to the period (0 = oneshot mode) > + * > + * Helper function for updating comparator, accumulator and period values. > + * > + * In periodic mode, HPET needs HPET_TN_SETVAL to be set before writing > + * to the Tn_CMP to update the accumulator. Then, HPET needs a second > + * write (with HPET_TN_SETVAL cleared) to Tn_CMP to set the period. > + * The HPET_TN_SETVAL bit is automatically cleared after the first write. > + * > + * For one-shot mode, HPET_TN_SETVAL does not need to be set. > + * > + * See the following documents: > + * - Intel IA-PC HPET (High Precision Event Timers) Specification > + * - AMD-8111 HyperTransport I/O Hub Data Sheet, Publication # 24674 > + */ > +void hpet_set_comparator(int num, unsigned int cmp, unsigned int period) > +{ > + if (period) { > + unsigned int v = hpet_readl(HPET_Tn_CFG(num)); > + > + hpet_writel(v | HPET_TN_SETVAL, HPET_Tn_CFG(num)); > + } > + > + hpet_writel(cmp, HPET_Tn_CMP(num)); > + > + if (!period) > + return;
TBH, I hate this conditional handling. What's wrong with two functions?
> + > + /* > + * This delay is seldom used: never in one-shot mode and in periodic > + * only when reprogramming the timer. > + */ > + udelay(1); > + hpet_writel(period, HPET_Tn_CMP(num)); > +} > +EXPORT_SYMBOL_GPL(hpet_set_comparator);
Why is this exported? Which module user needs this?
Thanks,
tglx
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