From a5bef810ad9816a3a8e500d8832be77d52903a12 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 29 Apr 2012 22:54:17 +0200 Subject: PM / Domains: Rework default device stop governor function, v2 The existing default device stop governor function for PM domains, default_stop_ok(), is supposed to check whether or not the device's PM QoS latency constraint will be violated if the device is stopped by pm_genpd_runtime_suspend(). However, the computations carried out by it don't reflect the definition of the PM QoS latency constrait in Documentation/ABI/testing/sysfs-devices-power. Make default_stop_ok() follow the definition of the PM QoS latency constrait. In particular, make it take the device's start and stop latencies correctly. Add a new field, effective_constraint_ns, to struct gpd_timing_data and use it to store the difference between the device's PM QoS constraint and its resume latency for use by the device's parent (the effective_constraint_ns values for the children are used for computing the parent's one along with its PM QoS constraint). Remove the break_even_ns field from struct gpd_timing_data, because it's not used any more. Signed-off-by: Rafael J. Wysocki --- drivers/base/power/domain.c | 1 + drivers/base/power/domain_governor.c | 53 +++++++++++++++++++++++++++++++++--- 2 files changed, 50 insertions(+), 4 deletions(-) (limited to 'drivers/base') diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 73ce9fbe9839..3c6e94fe058a 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -506,6 +506,7 @@ static int pm_genpd_runtime_suspend(struct device *dev) if (dev_gpd_data(dev)->always_on) return -EBUSY; + dev_gpd_data(dev)->td.effective_constraint_ns = -1; stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL; if (stop_ok && !stop_ok(dev)) return -EBUSY; diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c index 66a265bf5867..a67f157a7a74 100644 --- a/drivers/base/power/domain_governor.c +++ b/drivers/base/power/domain_governor.c @@ -14,6 +14,31 @@ #ifdef CONFIG_PM_RUNTIME +static int dev_update_qos_constraint(struct device *dev, void *data) +{ + s64 *constraint_ns_p = data; + s32 constraint_ns = -1; + + if (dev->power.subsys_data && dev->power.subsys_data->domain_data) + constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns; + + if (constraint_ns < 0) { + constraint_ns = dev_pm_qos_read_value(dev); + constraint_ns *= NSEC_PER_USEC; + } + if (constraint_ns == 0) + return 0; + + /* + * constraint_ns cannot be negative here, because the device has been + * suspended. + */ + if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0) + *constraint_ns_p = constraint_ns; + + return 0; +} + /** * default_stop_ok - Default PM domain governor routine for stopping devices. * @dev: Device to check. @@ -21,14 +46,34 @@ bool default_stop_ok(struct device *dev) { struct gpd_timing_data *td = &dev_gpd_data(dev)->td; + s64 constraint_ns; dev_dbg(dev, "%s()\n", __func__); - if (dev->power.max_time_suspended_ns < 0 || td->break_even_ns == 0) - return true; + constraint_ns = dev_pm_qos_read_value(dev); + if (constraint_ns < 0) + return false; + + constraint_ns *= NSEC_PER_USEC; + /* + * We can walk the children without any additional locking, because + * they all have been suspended at this point. + */ + if (!dev->power.ignore_children) + device_for_each_child(dev, &constraint_ns, + dev_update_qos_constraint); - return td->stop_latency_ns + td->start_latency_ns < td->break_even_ns - && td->break_even_ns < dev->power.max_time_suspended_ns; + if (constraint_ns > 0) { + constraint_ns -= td->start_latency_ns; + if (constraint_ns == 0) + return false; + } + td->effective_constraint_ns = constraint_ns; + /* + * The children have been suspended already, so we don't need to take + * their stop latencies into account here. + */ + return constraint_ns > td->stop_latency_ns || constraint_ns == 0; } /** -- cgit