Messages in this thread Patch in this message |  | | | From | "Rafael J. Wysocki" <> | | Subject | [PATCH 1/3] PM / Domains: Rework default device stop governor function | | Date | Tue, 24 Apr 2012 23:50:04 +0200 |
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From: Rafael J. Wysocki <rjw@sisk.pl>
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 <rjw@sisk.pl> --- drivers/base/power/domain_governor.c | 46 +++++++++++++++++++++++++++++++---- include/linux/pm_domain.h | 2 - 2 files changed, 42 insertions(+), 6 deletions(-) Index: linux/drivers/base/power/domain_governor.c =================================================================== --- linux.orig/drivers/base/power/domain_governor.c +++ linux/drivers/base/power/domain_governor.c @@ -14,6 +14,21 @@ #ifdef CONFIG_PM_RUNTIME +static int dev_update_qos_constraint(struct device *dev, void *data) +{ + s64 *constraint_ns_p = data; + struct gpd_timing_data *td; + + if (!(dev->power.subsys_data && dev->power.subsys_data->domain_data)) + return 0; + + td = &dev_gpd_data(dev)->td; + if (!*constraint_ns_p || td->effective_constraint_ns < *constraint_ns_p) + *constraint_ns_p = td->effective_constraint_ns; + + return 0; +} + /** * default_stop_ok - Default PM domain governor routine for stopping devices. * @dev: Device to check. @@ -21,14 +36,35 @@ 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; - - return td->stop_latency_ns + td->start_latency_ns < td->break_even_ns - && td->break_even_ns < dev->power.max_time_suspended_ns; + td->effective_constraint_ns = -1; + 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); + + 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; } /** Index: linux/include/linux/pm_domain.h =================================================================== --- linux.orig/include/linux/pm_domain.h +++ linux/include/linux/pm_domain.h @@ -93,7 +93,7 @@ struct gpd_timing_data { s64 start_latency_ns; s64 save_state_latency_ns; s64 restore_state_latency_ns; - s64 break_even_ns; + s64 effective_constraint_ns; }; struct generic_pm_domain_data {
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