From 327adaedf2218b0e318eb393aa79cf2be64c199f Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 11 Feb 2014 00:35:29 +0100 Subject: PM / QoS: Add no_constraints_value field to struct pm_qos_constraints Add a new field, no_constraints_value, to struct pm_qos_constraints representing a list of PM QoS constraint requests to be returned by pm_qos_get_value() when that list of requests is empty. That field will be equal to default_value for all of the existing global PM QoS classes and for the resume latency device PM QoS type, but it will be different from default_value for the new latency tolerance device PM QoS type introduced by the next changeset. Signed-off-by: Rafael J. Wysocki --- kernel/power/qos.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/power') diff --git a/kernel/power/qos.c b/kernel/power/qos.c index 8dff9b48075a..e23ae38e647f 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -66,6 +66,7 @@ static struct pm_qos_constraints cpu_dma_constraints = { .list = PLIST_HEAD_INIT(cpu_dma_constraints.list), .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, + .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .type = PM_QOS_MIN, .notifiers = &cpu_dma_lat_notifier, }; @@ -79,6 +80,7 @@ static struct pm_qos_constraints network_lat_constraints = { .list = PLIST_HEAD_INIT(network_lat_constraints.list), .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE, .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE, + .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE, .type = PM_QOS_MIN, .notifiers = &network_lat_notifier, }; @@ -93,6 +95,7 @@ static struct pm_qos_constraints network_tput_constraints = { .list = PLIST_HEAD_INIT(network_tput_constraints.list), .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE, .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE, + .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE, .type = PM_QOS_MAX, .notifiers = &network_throughput_notifier, }; @@ -128,7 +131,7 @@ static const struct file_operations pm_qos_power_fops = { static inline int pm_qos_get_value(struct pm_qos_constraints *c) { if (plist_head_empty(&c->list)) - return c->default_value; + return c->no_constraint_value; switch (c->type) { case PM_QOS_MIN: -- cgit v1.2.3 From 2d984ad132a87ca2112f81f21039493176a8bca0 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 11 Feb 2014 00:35:38 +0100 Subject: PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki --- kernel/power/qos.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'kernel/power') diff --git a/kernel/power/qos.c b/kernel/power/qos.c index e23ae38e647f..884b77058864 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -173,6 +173,7 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node, { unsigned long flags; int prev_value, curr_value, new_value; + int ret; spin_lock_irqsave(&pm_qos_lock, flags); prev_value = pm_qos_get_value(c); @@ -208,13 +209,15 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node, trace_pm_qos_update_target(action, prev_value, curr_value); if (prev_value != curr_value) { - blocking_notifier_call_chain(c->notifiers, - (unsigned long)curr_value, - NULL); - return 1; + ret = 1; + if (c->notifiers) + blocking_notifier_call_chain(c->notifiers, + (unsigned long)curr_value, + NULL); } else { - return 0; + ret = 0; } + return ret; } /** -- cgit v1.2.3