On 02/12, Lina Iyer wrote:
> @@ -52,6 +55,76 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
> return res;
> }
>
> +static bool cpu_pd_down_ok(struct dev_pm_domain *pd)
> +{
> + struct generic_pm_domain *genpd = pd_to_genpd(pd);
> + struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd);
> + int qos = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
> + u64 sleep_ns;
> + ktime_t earliest, next_wakeup;
> + int cpu;
> + int i;
> +
> + /* Reset the last set genpd state, default to index 0 */
> + genpd->state_idx = 0;
> +
> + /* We dont want to power down, if QoS is 0 */
> + if (!qos)
> + return false;
> +
> + /*
> + * Find the sleep time for the cluster.
> + * The time between now and the first wake up of any CPU that
> + * are in this domain hierarchy is the time available for the
> + * domain to be idle.
> + */
> + earliest = ktime_set(KTIME_SEC_MAX, 0);
> + for_each_cpu_and(cpu, cpu_pd->cpus, cpu_online_mask) {
We're not worried about hotplug happening in parallel because
preemption is disabled here?
> + next_wakeup = tick_nohz_get_next_wakeup(cpu);
> + if (earliest.tv64 > next_wakeup.tv64)
if (ktime_before(next_wakeup, earliest))
> + earliest = next_wakeup;
> + }
> +
> + sleep_ns = ktime_to_ns(ktime_sub(earliest, ktime_get()));
> + if (sleep_ns <= 0)
> + return false;
> +
> + /*
> + * Find the deepest sleep state that satisfies the residency
> + * requirement and the QoS constraint
> + */
> + for (i = genpd->state_count - 1; i >= 0; i--) {
> + u64 state_sleep_ns;
> +
> + state_sleep_ns = genpd->states[i].power_off_latency_ns +
> + genpd->states[i].power_on_latency_ns +
> + genpd->states[i].residency_ns;
> +
> + /*
> + * If we cant sleep to save power in the state, move on
s/cant/can't/
> + * to the next lower idle state.
> + */
> + if (state_sleep_ns > sleep_ns)
> + continue;
> +
> + /*
> + * We also dont want to sleep more than we should to
s/dont/don't/
> + * gaurantee QoS.
> + */
> + if (state_sleep_ns < (qos * NSEC_PER_USEC))
Maybe we should make qos into qos_ns? Presumably the compiler
would hoist out the multiplication here, but it doesn't hurt to
do it explicitly.
> + break;
> + }
> +
> + if (i >= 0)
> + genpd->state_idx = i;
> +
> + return (i >= 0) ? true : false;
Just return i >= 0?
--
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