260 строки
7.2 KiB
C
260 строки
7.2 KiB
C
/*
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* drivers/base/power/domain_governor.c - Governors for device PM domains.
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*
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* Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
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*
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* This file is released under the GPLv2.
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*/
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#include <linux/kernel.h>
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#include <linux/pm_domain.h>
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#include <linux/pm_qos.h>
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#include <linux/hrtimer.h>
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static int dev_update_qos_constraint(struct device *dev, void *data)
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{
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s64 *constraint_ns_p = data;
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s64 constraint_ns;
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if (dev->power.subsys_data && dev->power.subsys_data->domain_data) {
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/*
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* Only take suspend-time QoS constraints of devices into
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* account, because constraints updated after the device has
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* been suspended are not guaranteed to be taken into account
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* anyway. In order for them to take effect, the device has to
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* be resumed and suspended again.
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*/
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constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
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} else {
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/*
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* The child is not in a domain and there's no info on its
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* suspend/resume latencies, so assume them to be negligible and
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* take its current PM QoS constraint (that's the only thing
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* known at this point anyway).
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*/
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constraint_ns = dev_pm_qos_read_value(dev);
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constraint_ns *= NSEC_PER_USEC;
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}
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if (constraint_ns < *constraint_ns_p)
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*constraint_ns_p = constraint_ns;
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return 0;
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}
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/**
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* default_suspend_ok - Default PM domain governor routine to suspend devices.
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* @dev: Device to check.
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*/
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static bool default_suspend_ok(struct device *dev)
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{
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struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
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unsigned long flags;
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s64 constraint_ns;
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dev_dbg(dev, "%s()\n", __func__);
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spin_lock_irqsave(&dev->power.lock, flags);
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if (!td->constraint_changed) {
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bool ret = td->cached_suspend_ok;
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spin_unlock_irqrestore(&dev->power.lock, flags);
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return ret;
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}
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td->constraint_changed = false;
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td->cached_suspend_ok = false;
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td->effective_constraint_ns = 0;
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constraint_ns = __dev_pm_qos_read_value(dev);
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spin_unlock_irqrestore(&dev->power.lock, flags);
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if (constraint_ns == 0)
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return false;
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constraint_ns *= NSEC_PER_USEC;
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/*
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* We can walk the children without any additional locking, because
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* they all have been suspended at this point and their
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* effective_constraint_ns fields won't be modified in parallel with us.
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*/
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if (!dev->power.ignore_children)
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device_for_each_child(dev, &constraint_ns,
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dev_update_qos_constraint);
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if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) {
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/* "No restriction", so the device is allowed to suspend. */
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td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
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td->cached_suspend_ok = true;
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} else if (constraint_ns == 0) {
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/*
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* This triggers if one of the children that don't belong to a
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* domain has a zero PM QoS constraint and it's better not to
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* suspend then. effective_constraint_ns is zero already and
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* cached_suspend_ok is false, so bail out.
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*/
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return false;
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} else {
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constraint_ns -= td->suspend_latency_ns +
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td->resume_latency_ns;
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/*
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* effective_constraint_ns is zero already and cached_suspend_ok
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* is false, so if the computed value is not positive, return
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* right away.
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*/
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if (constraint_ns <= 0)
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return false;
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td->effective_constraint_ns = constraint_ns;
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td->cached_suspend_ok = true;
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}
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/*
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* The children have been suspended already, so we don't need to take
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* their suspend latencies into account here.
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*/
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return td->cached_suspend_ok;
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}
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static bool __default_power_down_ok(struct dev_pm_domain *pd,
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unsigned int state)
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{
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struct generic_pm_domain *genpd = pd_to_genpd(pd);
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struct gpd_link *link;
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struct pm_domain_data *pdd;
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s64 min_off_time_ns;
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s64 off_on_time_ns;
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off_on_time_ns = genpd->states[state].power_off_latency_ns +
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genpd->states[state].power_on_latency_ns;
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min_off_time_ns = -1;
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/*
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* Check if subdomains can be off for enough time.
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*
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* All subdomains have been powered off already at this point.
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*/
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list_for_each_entry(link, &genpd->master_links, master_node) {
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struct generic_pm_domain *sd = link->slave;
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s64 sd_max_off_ns = sd->max_off_time_ns;
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if (sd_max_off_ns < 0)
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continue;
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/*
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* Check if the subdomain is allowed to be off long enough for
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* the current domain to turn off and on (that's how much time
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* it will have to wait worst case).
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*/
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if (sd_max_off_ns <= off_on_time_ns)
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return false;
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if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
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min_off_time_ns = sd_max_off_ns;
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}
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/*
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* Check if the devices in the domain can be off enough time.
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*/
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list_for_each_entry(pdd, &genpd->dev_list, list_node) {
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struct gpd_timing_data *td;
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s64 constraint_ns;
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/*
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* Check if the device is allowed to be off long enough for the
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* domain to turn off and on (that's how much time it will
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* have to wait worst case).
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*/
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td = &to_gpd_data(pdd)->td;
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constraint_ns = td->effective_constraint_ns;
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/*
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* Zero means "no suspend at all" and this runs only when all
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* devices in the domain are suspended, so it must be positive.
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*/
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if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS)
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continue;
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if (constraint_ns <= off_on_time_ns)
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return false;
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if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
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min_off_time_ns = constraint_ns;
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}
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/*
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* If the computed minimum device off time is negative, there are no
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* latency constraints, so the domain can spend arbitrary time in the
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* "off" state.
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*/
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if (min_off_time_ns < 0)
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return true;
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/*
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* The difference between the computed minimum subdomain or device off
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* time and the time needed to turn the domain on is the maximum
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* theoretical time this domain can spend in the "off" state.
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*/
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genpd->max_off_time_ns = min_off_time_ns -
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genpd->states[state].power_on_latency_ns;
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return true;
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}
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/**
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* default_power_down_ok - Default generic PM domain power off governor routine.
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* @pd: PM domain to check.
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*
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* This routine must be executed under the PM domain's lock.
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*/
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static bool default_power_down_ok(struct dev_pm_domain *pd)
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{
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struct generic_pm_domain *genpd = pd_to_genpd(pd);
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struct gpd_link *link;
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if (!genpd->max_off_time_changed)
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return genpd->cached_power_down_ok;
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/*
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* We have to invalidate the cached results for the masters, so
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* use the observation that default_power_down_ok() is not
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* going to be called for any master until this instance
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* returns.
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*/
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list_for_each_entry(link, &genpd->slave_links, slave_node)
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link->master->max_off_time_changed = true;
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genpd->max_off_time_ns = -1;
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genpd->max_off_time_changed = false;
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genpd->cached_power_down_ok = true;
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genpd->state_idx = genpd->state_count - 1;
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/* Find a state to power down to, starting from the deepest. */
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while (!__default_power_down_ok(pd, genpd->state_idx)) {
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if (genpd->state_idx == 0) {
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genpd->cached_power_down_ok = false;
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break;
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}
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genpd->state_idx--;
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}
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return genpd->cached_power_down_ok;
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}
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static bool always_on_power_down_ok(struct dev_pm_domain *domain)
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{
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return false;
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}
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struct dev_power_governor simple_qos_governor = {
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.suspend_ok = default_suspend_ok,
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.power_down_ok = default_power_down_ok,
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};
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/**
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* pm_genpd_gov_always_on - A governor implementing an always-on policy
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*/
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struct dev_power_governor pm_domain_always_on_gov = {
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.power_down_ok = always_on_power_down_ok,
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.suspend_ok = default_suspend_ok,
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};
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